Boeing Flight Operations SyBoeing Flight Operations Symposiummposium
**** Hidden Message ***** Boeing Flight Operations SymposiumMarch 30 - April 1, 1999
Seattle, Washington
737 Caucus Summary Report
1 July 7, 1999
AIR SYSTEMS
1. Why is the step “Isolation Valve........AUTO” included in the Before Start checklist on
737 airplanes?
<ANSWER> Two APUs, the GTCP36-280(B) installed on some 737 current generation
(CG) airplanes and the Allied Signal 131-9(B) installed on the 737NG, can be
used to operate both air conditioning packs on the ground. 737 Technical
Bulletin 99-1 dated 12 February 99, provided details about APU Operating
Practices. The isolation valve must be open in order for both packs to operate
on the ground. However, for takeoff, the isolation valve must be closed. To
ensure the isolation valve switch is correctly positioned to “Auto” for takeoff
after two pack operation, we added the “Isolation Valve........AUTO” step to
the After Start Checklist.
ANTI-ICE, RAIN
2. Is it possible to design a bleed air or hydraulic fluid heat exchanger to heat fuel on the
737 NG instead of using the electrical blankets to deal with non-environmental wing
icing?
<ANSWER> Boeing has entered this issue into the Service Related Problem (SRP) system,
which is a formal system for tracking and resolving service issues. As a routine
part of the process, all possible methods of warming the fuel and other possible
approaches are being evaluated. Periodic coordination with affected customer
airlines is a routine part of the SRP process. An airline working group meeting
on Wing Upper Surface Non-Environmental Icing took place in Seattle on June
10, 1999.
3. Is preliminary data on the cold-soak fuel wing icing issue for the 737NG available at
this time? If not, when will this data be available?
<ANSWER> Preliminary data is being compiled at this time and is not available for release.
The SRP board is considering creating a “predicted icing table” with the data
available. An airline working group meeting on Wing Upper Surface Non-
Environmental Icing took place in Seattle on June 10, 1999.
4. What level of wing tank fuel will result in no contact with the wing upper surface skin
on the 737 NG?
<ANSWER> Wing tank fuel will not contact the upper wing surface when quantity is less that
approximately 400 gallons (2600 lbs. / 1180 kgs.) per tank.
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5. What is the status of the aerodynamics study on the effects of inflight cold-soak fuel
wing icing for the 737NG?
<ANSWER> The study is in work. Final numbers are not yet available but the study has
identified no safety issue. Normal maneuvering capability and stick shaker stall
warning continues to be available using normal approach speeds.
6. Boeing hasn’t addressed frost/ice on vertical fin near body juncture on the 737NG.
What is status?
<ANSWER> Although we lack adequate data at this time, Boeing is currently reviewing this
issue as a potential SRP candidate. If accepted, the issue will be dealt with as a
separate SRP item. Operators who have experienced this type of icing, should
send all pertinent data to Boeing.
7. Can Boeing provide comments on rain repellent replacements and possibility of an
NTO for new the Airbus product?
<ANSWER> Boeing is aware that a replacement rain repellent developed by Le Bozec has
been certified by Airbus and is currently being delivered on Airbus model
airplanes. Additionally, Boeing is aware that Airbus has developed retrofit
instructions for their models. Boeing does not plan to continue the review and/or
certification effort for a replacement rain repellent fluid for Boeing model
airplanes. This decision has been made for the following reasons: 1) All Boeing
model airplanes are certified to operate with windshield wipers only. 2) Rain
repellents are considered an enhancement and Boeing no longer delivers fluid
rain repellent systems on production airplanes except for the 737-300/-400/-
500 models. 3) Boeing delivers external rain repellent coatings on all production
model airplanes and feels this configuration is the most appropriate direction for
rain repellent systems in the future. This determination takes into account
multiple design and economic considerations for this issue. Boeing service letter
737-30-009C dated 28 June 1996 provides further information regarding
external coatings. 4) In order for Boeing to provide technical comments on a
fluid Rainboe replacement system, similar testing to that discussed in Boeing
Document, D6-81867 (26 November 1996) - Assessment Of Rainboe Rain
Repellent Systems Installed On Boeing Commercial Airplanes must be
conducted. Boeing developed this document for Rainboe after significant study
and testing. The document was prepared by a team of experts that included
Boeing personnel and industrial hygiene consultants. The team examined the
Rainboe distribution system, crew compartment air flow characteristics, toxicity
information on the chemical constituents of Rainboe and known reports of
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Seattle, Washington
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Rainboe leakage. Events associated with the reports were analyzed to identify
potential leak location, leak characteristics and associated health concerns.
Analysis results were used to consider plausible worst-case scenarios of
Rainboe leakage. Once determined, the types of leaks associated with these
scenarios were simulated in a controlled laboratory environment utilizing
production rain repellent hardware.
At this time, Boeing does not plan to further pursue this level of study and
testing on the Le Bozec rain repellent product. Boeing will provide a copy of
Document, D6-81867 (26 November 1996) upon request for review and
information. Two alternatives exist to certify the replacement fluid and Boeing
has communicated these items directly to Le Bozec: 1) Le Bozec could fund the
testing and development of a study and publication similar to the Boeing
document. 2) Le Bozec could independently obtain their own supplemental type
certificate for the replacement product to be installed on Boeing model
airplanes.
COMMUNICATIONS
8. When will VHF/HF frequency limitations contained in the 737NG AFM be eliminated?
<ANSWER> The VHF limitation is the result of interference caused by the EEC that affects
frequency 120.00. The interference is eliminated by installing an overbraided
EEC wire bundle. Airplanes with line number LN147 and beyond have the new
wire bundles installe d at delivery. Airplanes with line numbers preceding LN147
must be modified by service bulletin #SB 737-73-1010 before the AFM
limitation can be removed. Operators should notify Boeing when fleet
modifications are complete so that manuals can be updated.
HF frequency limitations are the result of interference caused by cabin
entertainment systems. Boeing is working with the vendors who provide these
systems in an effort to reduce this interference to acceptable levels. No relief
from these limitations is available at this time.
ELECTRICAL
9. If a generator fails during approach, is the corresponding flight director automatically
removed following autopilot disengagement?
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<ANSWER> Yes, the power transfer associated with a generator failure causes the autopilot
to disconnect and lets the FCCs know that there is only one source of power. If
the generator fails during approach, the autopilot disconnects and the flight
director (F/D) on the failed side will bias out of view. However, if the generator
failure occurs below 800 feet during a dual F/D approach (autopilot not
engaged), the F/D on the failed side will not bias out of view because the FCC
on the side with the operating generator will provide guidance outputs to both
flight directors.
10. If the battery switch is positioned to “OFF” on ground and with normal power sources
available, will AC transfer busses remain powered?
<ANSWER> The AC transfer busses behave differently on the 737 “classic” and the 737NG
as follows:
Case 1: Airplane powered from Ground Power (Grnd Pwr) and Batt Sw
turned OFF:
737-3/4/500: Grnd Pwr drops off. Transfer Busses not powered.
737-6/7/800: Grnd Pwr stays on. Transfer Busses powered.
Reason for difference: On 737-3/4/500, Bus Protection Panel
depends on DC backup power from ship's battery for protection
circuits to operate in event of a major AC fault. On 737-6/7/800,
Bus Power Control Unit is specified to “...be capable of normal ....
operation (control and protection) without the need for a backup
supply.”
Case 2: Airplane powered from APU generator and Batt Sw turned OFF:
737-3/4/5/6/7/800: APU shuts down (Ground ops only). Transfer
Busses not powered.
Reason: With Batt Sw OFF, APU fire detection is inop and airplane
may be unattended.
Case 3: Airplane powered from engine generators and Batt Sw turned OFF:
737-3/4/5/6/7/800: Transfer busses powered.
ENGINES, APU
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11. The 737 Shutdown checklist states “Pumps..........OFF”. How does Boeing reconcile
this step with the recommendation that a fuel pump be left on when the APU is
running?
<ANSWER> As stated in the Operations Manual, Supplementary Procedures Section, in the
notes under the APU Start Procedure, there are two reasons to have a fuel
pump on while the APU is running: 1) If extended APU operation is required on
the ground and fuel is loaded in the center tank, place the left center tank fuel
pump switch ON to prevent a fuel imbalance before takeoff. 2) Whenever the
APU is operating and AC electrical power is on the airplane busses, extended
service life of the APU fuel control unit can be realized by operating at least one
fuel boost pump to supply fuel under pressure to the APU. If the APU is to be
left running for an extended period of time, a fuel boost pump should be left on.
12. Does Boeing have a recommendation concerning starting engines in tailwind
situations?
<ANSWER> When starting the engines in tailwind conditions, Boeing recommends making a
normal start, expecting a longer cranking time to ensure N1 is rotating in the
correct direction before moving the start lever. A higher than normal EGT
should be expected, yet the same limits and procedures should apply.
13. New HMU production installation at line number 268 equates to what date?
<ANSWER> The new (PO7) HMU will be incorporated on production aircraft starting with
line No. 264 (YC607) which delivered in the middle of May, 1999. All aircraft
after Line No. 264 will deliver with PO7 HMUs.
14. What about cost of retrofit?
<ANSWER> Retrofit replacement of the PO6 with the PO7 HMU will be completed at no
cost to the customer.
15. What is the EEC temperature crossover for flight idle?
<ANSWER> EEC software version 7.B.J increased the minimum inflight idle speed to the
lesser of a constant physical 10,400 rpm (71.9%) N2 speed or the approach
idle schedule. The approach idle schedule provides a constant corrected
N2C25 speed which is a function of altitude and airspeed. Since the approach
idle schedule provides constant corrected (N2C25) speed, the associated
physical approach idle N2 speed is proportional the square root of the station
2.5 temperature. The approach idle schedule also increases as a function of
altitude. The combination of cold day temperatures and low altitude operation
can result in physical approach idle speeds near or below 10,400 rpm, resulting
in little or no approach idle shift being observable.
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16. The 7BJ EEC software modification does not appear to fix N2 tone if encountered
above FL200. Why?
<ANSWER> The idle N2 increase starts at FL200 and is ramped up to a maximum increase
at 15,000 ft MSL. This was done to minimize the impact on descent
performance and because most of the documented cases of N2 tone occurred
at altitudes below FL200.
17. Has Boeing looked at a soft pylon (isolation mounts) to help reduce engine noise and
vibration?
<ANSWER> Isolation mounts were removed from the 737NG to reduce maintenance costs
(replacement). The current design does not have the capability for installation of
isolation mounts.
18. What is the purpose of the proposed AVM coefficient schedule change?
<ANSWER> The current CFM 56-7 AVM coefficients are the same ones used on the CFM
56-3 engines. The core vibration sensors on the -7 are more sensitive than
those on the -3. For a similar level of core vibration, the -7 would show twice
the amount of AVM gage reading as the -3. Since flight and maintenance
procedures are based upon AVM indications, it was felt that changing the
coefficients would make the indications and thus procedures more consistent
between the engines.
FLIGHT CONTROLS
19. Why does the Speed Trim system sometimes appear to trim opposite the desired
direction?
<ANSWER> The Speed Trim System (STS) is used to increase the column forces needed for
speed stability. The purpose of the STS is to provide positive speed stability
characteristics to the pilot. In other words, the STS adjusts stick force so the
pilot must provide significant amount of pull force to reduce airspeed or a
significant amount of push force to increase airspeed.
The flight regime where the STS is needed is low airspeeds, aft cg, high power
settings and light gross weights. The inputs to the STS are: stabilizer position to
estimate cg, N1 to estimate thrust and airspeed to determine how much
stabilizer trim is needed to provide the desired speed stability characteristics.
The speed trim system begins to trim the stabilizer in the direction calculated to
provide the pilot positive speed stability characteristics. Since pilots typically
attempt to trim stick force to zero and the STS is attempting to trim to positive
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Seattle, Washington
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stick force, STS trim direction may be opposite the direction the pilot is
trimming.
20. Would using a higher flap setting for very low take off weights (B737-400 T.O. Wt <
45000 kgs., B737-800 T.O. Wt < 55000 kgs.) help in minimizing the risk of tail strike?
Would using flap 15 help in minimizing?
<ANSWER> The 737 Flight Crew Training Manual (FCTM) revision dated 1April 99
contains considerable data concerning this issue in Section 2, pages 2.21 -
2.22. For example, the charts show that 3 additional inches of tail clearance can
be gained by using a flaps 15 takeoff configuration on a 737-800. Operational
notes in this section state, “Flaps 1 and flaps 5 takeoffs have the least clearance.
Consider using a larger flap setting for takeoffs at light gross weights.” As
always, airport takeoff analysis data must be considered in making a
determination of appropriate takeoff flap settings.
FLIGHT INSTRUMENTS, DISPLAYS
21. With a dual display unit failure (737NG with EFIS/MAP format), compacted display is
shown on both sides. Is LNAV still available or is HDG SEL and conventional
navigation preferred?
<ANSWER> LNAV guidance will still be available through the autopilot or flight director.
Due to lack of MAP display, pilot must monitor cross-track error on the FMC
CDU. Progress Page 3/3 displays wind, track, path and speed data. This page
displays present cross-track error from the FMC flight plan course.
22. The 737 MMEL does not provide any dispatch relief for a CDS FAULT annunciation
on the 737NG. What is the status of Boeing’s efforts to obtain dispatch relief for this
annunciation?
<ANSWER> The CDS FAULT annunciation indicates system faults that do not allow
dispatch under the certification basis for the 737NG. Therefore, Boeing has not
asked for and does not anticipate receiving any dispatch relief for the CDS
FAULT annunciation. However, Boeing is pursuing a software upgrade that will
allow MMEL relief for the CDS MAINT annunciation on the 737NG. The
upgrade designated, “CDS Blockpoint 99”, should be available during the last
quarter of 1999. The 737 MMEL will be revised accordingly when software
certification is complete.
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FLIGHT MANAGEMENT, NAVIGATION
23. 737NG speed limit in the FMC is Mach 0.805 - this is too slow. This penalizes cruise
speed. Speed limit to prevent getting clacker on older 737 models is Mach 0.82. Why
are these values different?
<ANSWER> Mach .805 speed limit (approximately 7 kts below Mach .82) was imposed to
prevent the airplane from exceeding Mach .82 limit speed as it starts to descend
from cruise in VNAV. Engineering is reviewing this limit to determine if a
change can be accommodated.
24. Is FMC software upgrade 10 also available for the 737 “classic”?
<ANSWER> Yes, 737CG FMCs may be upgraded to U10.X software. For airplanes
equipped with U1.XX, U5 or U6, both a hardware and software change is
required. For airplanes with U7 or U8, memory upgrades may be required if
not previously incorporated, as well as a software change. Boeing’s Service
Bulletin Organization should be contacted about software upgrades. Smith
Industries should be contacted for specific details about upgrading FMC
hardware.
25. What is the latest information regarding software restart anomalies on U10 FMC
operating systems? Does Boeing have any data on fleet experiences?
<ANSWER> Although software restarts and downmodes to single FMC operation are
undesirable, they probably cannot be totally eliminated with current technology.
However, in each FMC update, improvements are made to eliminate as many
of these events as possible. U10.2A should have fewer events than U10.1,
which has fewer than U10.0. Additional improvements will be incorporated into
U10.3. A critical tool in the reduction of these events is built in test equipment
(BITE) data that can be downloaded from the FMC via the data loader.
Software has been incorporated in the FMC to record data during these events
to help in identifying the causes.
After any event, especially software restarts, data should be downloaded from
the FMCs and forwarded to Smiths Industries and Boeing. In dual FMC
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installations, it is important to download the data from both FMCs.
To date, Boeing has received data from 44 software restart events in the field.
We have identified 15 different causes for these 44 events. Data from one
airline indicates 1.6 restarts per airplane-month for U10.1 on 737 “classic”
airplanes. Another operator has provided data from U10.2 that indicates a
software restart every time an aircraft lands while the flight plan contains a
missed approach consisting of a single vector leg. The same operator has had
one other software restart on the ground where a problem was encountered
when a STAR was entered along with a certain company route.
FUEL
26. Can Boeing provide more background information on alert bulletin regarding center
tank float switch deactivation?
<ANSWER> Alert Bulletin 737-28A1132 addresses AD 99-05-12. This airworthiness
directive (AD) is applicable to certain Boeing Model 737-100, -200, -300, -
400, and -500 series airplanes. The AD requires removal of the float switch and
wiring and inspection of the float switch wiring in the center fuel tank to detect
discrepancies, and either reinstallation of the existing float switch and wiring, or
replacement of the float switch and wiring with a new float switch and wiring.
This action also requires installation of Teflon sleeving over the wiring of the
float switch. In lieu of the above mentioned requirements, this AD requires
deactivation of the float switch, accomplishment of specific fueling procedures,
and installation of caution signs. The AD was released in response to reports
indicating that chafing of the direct current (DC) powered float switch wiring
insulation in the center fuel tank has occurred on several airplanes. The AD is
intended to detect and correct the chafing and prevent arcing from the wiring to
the in-tank conduit which could present an ignition source inside the fuel tank.
27. What information is available on 737NG center tank fuel boost pump loss of prime
characteristics? Have any Operations Manual revisions been incorporated?
<ANSWER> The location of the fuel pump inlets in the 737NG center fuel tank can cause
one pump inlet to “uncover” before the other. Steeper than normal body
attitudes during climb and descent can increase the delay between the forward
and aft pump low pressure indications. Engineering data indicate that a pump
must be uncovered for 8 -15 minutes before loss of prime will occur. Predicted
fuel burn analysis during normal flight profiles shows minimum risk of this loss of
prime phenomenon occurring. Boeing continues to receive occasional reports of
loss of prime incidents and is investigating each one to determine if a system
design change is required. The reports have tended to occur during initial model
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introduction when the airplane may be flown with light loads and non-standard
fuel loads and routes. As operators gain familiarity with the fuel burn
characteristics of the airplane, incident reports have diminished.
The following note has been added to the fuel systems chapter in the Operations
Manual, “Fuel pump LOW PRESSURE lights may flicker when tank quantity is
low and the airplane is in a climb, descent, or on the ground with a nose-down
attitude.”
28. The 737 FUEL PUMP LOW PRESSURE checklist does not include a step which turns
off the pump associated with the LOW PRESSURE light. Why?
<ANSWER> We do not recommend turning the fuel boost pump OFF unless required by the
Operations Manual Normal or Supplementary procedure. The low pressure
light is activated by a pressure sensor located in the fuel line. When the fuel
pump low pressure light illuminates with significant fuel still in the tank, the pilot
cannot determine the cause of the light. Several cases exist where fuel is still
being pumped but the light illuminates. A Flight Operations Review Article, 737
Fuel Pump Low Pressure Indications After Takeoff dated April 10, 1991
contains further details about this subject.
LANDING GEAR
29. At very low gross weights the 737 classic encounters what seems like a longitudinal
resonance when taxiing at 17 kts. Changing taxi speed causes this speed oscillation to
disappear. Why?
<ANSWER> Occasionally during taxi-out, the 737-Classics experience “vibration/shudder”
at approximately 17-18 knots and the 737NGs at approximately 24 knots. The
cause of this vibration/shudder is attributed to tire 'cold set'. All tires using nylon
chord are susceptible to cold set and all airplane tires certified on Boeing
airplanes today use nylon chord. Tire cold set is a temporary flat spot that
occurs when an airplane with hot tires is parked and the tires cool to ambient
temperature. As noted in Goodyear's, Comprehensive Guide to Aircraft Tire
Care and Maintenance: “Loaded tires that are left stationary for any length of
time can develop temporary flat spots. The degree of this flat spotting depends
upon the load, tire deflection and temperature. Flat spotting is most severe and
more difficult to work out during cold weather. Under normal conditions, a flat
spot will disappear by the end of the taxi run.”
The effects of cold set tires can be felt in the airplane during taxi as speed
dependent vibration. This is because, at a particular speed, the revolutions of
the tire (and therefore the frequency of the flat spot induced vibration) equal the
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natural frequency of the landing gear structure. This causes resonance that
results in a noticeable vibration/shudder in the airplane. On the 737-Classics,
this occurs at approximately 17-18 knots. This vibration/shudder will reduce
when the taxi speed is either increased or decreased or as the tires warm during
taxi and the cold set is eliminated.
30. Does Boeing recommend not using autoland mode until the (737 NG) shimmy damper
is installed?
<ANSWER> No such limitation exists at this time. Certification limitations for the 737-600/-
700/-800 autopilot are not dependent on shimmy damper installation.
31. What is the duration of the wheel shudder?
<ANSWER> Shudder is described as fore and aft vibration of the main landing gear that
couples with the fuselage and typically lasts for less than a second.
32. Is the shudder data presented only for 737NG or “classic” also?
<ANSWER> Shudder is a vibration phenomena peculiar to the 737 NG. It should only be
seen on the -700 because of the unique combination of structural modes. Main
landing gear shimmy can occur on the 737 “classic” if the shimmy damper
malfunctions or is not maintained properly.
33. What’s the difference in shudder type between the -700 and -800?
<ANSWER> Shudder is defined as a -700 vibration mode only. It is considered a “signature”
of the -700 and should not occur on the -800 or -600. The gear motion on all
models is the same, but structural coupling does not occur because of the
different fuselage lengths.
34. Is Main Landing Gear shimmy a -700 problem or does it affect the -800 and -600?
<ANSWER> The 737-700 appears to be most susceptible to shimmy but because of the gear
design, all models of the 737NG have the potential to incur shimmy. 737-800
has had one reported incident. 737-600 has had 3 reported incidents.
35. Can Boeing address the different landing techniques to avoid shimmy?
<ANSWER> Shimmy occurs during low sink rate (< 1.5 fps) landings where the main landing
gear struts remain extended longer than normal. This is exacerbated if a “bunt”
technique is used where the pilot applies light forward pressure on the control
column just prior to touchdown. This technique results in the airplane floating
with the gear struts extended for a longer period of time than if a normal flare
technique is used. Pilots do not need to make “firm” touchdowns to avoid
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shimmy and can still strive for soft touchdowns if a normal flare technique is
used.
36. Does installation of the shimmy damper apply to all 737NG models?
<ANSWER> As currently planned, all -700 model aircraft will be fitted with shimmy
dampers. The schedule for incorporation on the -600 and -800 is under study
at Boeing.
37. Is the 737NG Shimmy Damper part number common with those installed on other
Boeing models?
<ANSWER> The original design for the 737 NG shimmy damper has been revised based
upon flight test results. The new design will have a unique part number that is
specific to the 737-600/700/800.
38. When will 737NG Shimmy Damper be installed on production airplanes?
<ANSWER> Incorporation of shimmy dampers on 737-700 production aircraft will start with
Line No. 406 and subsequent (delivers in November, 1999). Incorporation on
-600 and -800 aircraft is still under study but will be after Line No. 406.
39. Will this fix (damper) help the shudder problem?
<ANSWER> Shudder and shimmy involve different landing gear modes of motion. Based
upon engineering analysis, the dampers will not improve or eliminate main
landing gear shudder on the 737 NG. Shudder is defined by Boeing Engineering
as primarily a 737-700 phenomena that should not occur on the -600 and -800
models. Although Boeing and customer flight crews have reported shudder on
the -600 and -800, these reports of shudder may be attributed to heavily
damped shimmy vibration which is being erroneously identified as “shudder.” If
this is the case, the shimmy dampers should help eliminate vibration upon
landing.
40. Is the 737-700 certified for operation with 737-800 tires and brakes installed?
<ANSWER> The 737-700 is certificated for operation and can be delivered with 737-800
tires and brakes. This modification will require changes to the performance
documentation for the airplane including takeoff, landing and FMC data. If high
capacity brakes (Allied-Signal or BF Goodrich) are installed on the 737-700,
the brake category is “F.” Accordingly, the AFM and Ops Manual must be
changed to reflect category “F” performance. In addition, the Flight
Management Computer must be changed to reflect category “F” performance.
WARNING SYSTEMS
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41. Does Boeing have any plans to update the alert inhibit logic on 737 airplanes to more
closely match takeoff alert inhibit logic on EICAS equipped airplanes?
<ANSWER> Boeing currently has no plans to update 737 alert inhibit logic to more closely
match takeoff alert logic on EICAS equipped airplanes.
PERFORMANCE
42. When will 737 “classic” wet runway takeoff data be available?
<ANSWER> Wet runway data is available for the classics in the new QRH Performance
Inflight chapter. However, it was not part of the FAA certification requirements
for those airplane models so we do not present the data the same way it is
currently presented in the NG manuals.
If Operators choose to account for wet runway (remember, it is not required
under the older FAA certifications), they should use the advisory Slippery
Runway corrections to adjust their dry runway performance. The data
presented for “good” braking action approximates 1/2 of the dry braking
force (relative to dry) and is roughly equivalent to the wet runway data that
was required under CAA rules. Note there are differences between advisory
wet and CAA wet.
PROCEDURES
43. Why have through flight items with an asterisk been eliminated from normal checklists
in new format operations manuals?
<ANSWER> In developing the standardized new format (Jeppesen sized) Operations Manual
for all Boeing models, the asterisk was deleted for commonality. Also, we
observed on through flights, that many flight crews read the complete checklist
regardless of the asterisked items. Consequently, we decided to remove them.
44. Does Boeing have a procedure for a flap 15 “normal” landing?
<ANSWER> Although the 737 is certified for flap 15 “normal” landings, Boeing does not
publish a special procedure for this configuration. Operators who require flap
15 “normal” landing procedures should submit a proposed procedure to Boeing
for an NTO (no technical objection) consideration and then coordinate
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approval with their regulatory authority. The JAA does not allow flap 15
“normal” landings for the 737NG (AFM limitation).
45. Is the crosswind chart from the symposium presentation in the AFM and are the
values in this chart crosswind limits?
<ANSWER> The crosswind information chart contains guidelines not limits. The guidelines
were determined from analysis and piloted simulations not flight tests. This
information is not in the AFM since it is not a limit. This information is in the
latest version (April 1, 1999) of the Flight Crew Training Manual (FCTM) and
will be incorporated in the Operations Manual in a future revision.
46. What are Boeing guidelines for use of reverse thrust on crosswind landings?
<ANSWER> The Boeing crosswind guidelines include the effect of reverse thrust, including
reduction in recommended crosswind operation for asymmetric reverse thrust
conditions on contaminated runways. The 737 FCTM states, “To correct back
to the centerline, reduce reverse thrust to reverse idle and release the brakes.
This will minimize the reverse thrust side force component without the
requirement to go through a full reverser actuation cycle, and improve tire
cornering forces for realignment with the runway centerline. Use rudder pedal
steering and differential braking as required, to prevent over correcting past the
runway centerline. When re-established near the runway centerline, apply
maximum braking and symmetrical reverse thrust to stop the airplane.” This
modulation of reverse thrust may be necessary, particularly on slippery runways.
47. 17 knot crosswind on icy runway - was this demonstrated or analytical?
<ANSWER> The 17 kt landing crosswind guideline for the ice-no melting runway condition
was determined from analysis and piloted simulation evaluations.
48. Will Boeing delete the Flight Crew Training Manual (FCTM) recommendations about
“Crab Landings” in X-wind situations?
<ANSWER> Boeing has no plan to delete these recommendations from the 737 FCTM. The
recommendations are validated by flight test data, analysis and piloted
simulations and considered appropriate for use in the situations described.
49. Is crosswind (limits) information available for 30 meter runways?
<ANSWER> Yes, crosswind guidelines for operation on 30 meter runways have been
established for the 737-200 ADV, the 737-3/400, and the 737-6/7/800. This
data will be provided to customers who request a 30 meter runway
performance package appendix to the AFM.
50. Can Boeing provide a relationship between reported braking action reports and
crosswind limits?
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<ANSWER> No, a relationship between reported braking action and crosswinds has not
been established. Pilot reported braking action is subjective. Because of the
variability in reported braking action, there is no clear correlation between
reported braking action and the runway conditions used to establish the airplane
crosswind guidelines. It is believed that the runway condition categories of Dry,
Wet, Standing Water/Slush, Snow-No Melting, and Ice-No Melting, which
were used to establish our crosswind guidelines, provide the most technically
consistent means for relating runway condition and crosswind capability. Boeing
currently supports the industry/government efforts to improve the understanding
of runway contamination and the relationships to airplane operation.
51. During flap retraction, can we still use the speed tape “F” for flap retraction if airplane
is subject to revised block maneuver speeds?
<ANSWER> If it is the airline’s intent to comply with the revised maneuver speeds during
takeoff, then the speed tape “F” cannot be used. If you follow Boeing's
recommendation and only apply the revised maneuvering speeds to the
approach, then the “F” speeds can be used for flap retraction during takeoff.
52. Is it possible to display the “F” on the speed tape (737CG) for flap extension? If so,
can the display incorporate the revised speeds so that ‘block speeds’ would no longer
be required?
<ANSWER> This modification would require a large scale redesign of the display system
architecture and cannot be justified due to the temporary nature of the block
speed revisions.
53. In the “revised” block maneuver speeds for the 737 “classic”, was 20 knots added for
all flaps settings?
<ANSWER> No, 20 kts was only added to flaps 5 maneuvering speeds. At flap settings UP,
1 and 10, only 10 kts was required to keep the maneuvering speed above the
crossover speed.
54. On airplanes with speed tape, do we still need to make speed adjustments? Can we use
“green circle” +20 knots for example?
<ANSWER> Yes, speed adjustments are still required for approach maneuvering since the
FMC computed speeds are VREF based and for some combinations of
weights and flap settings, the FMC target speed will be below the crossover
speed. We do recommend that FMC target speeds, “F” symbol on the speed
tape, can be used for takeoff maneuvering and flap retraction since the exposure
time to a rudder event is typically of short duration.
55. Can we go back to the original speeds after the Rudder Pressure Reducer (RPR) is
installed?
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Seattle, Washington
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<ANSWER> The final analysis of the effects of the RPR will be completed in August, 1999.
Maneuver speeds for RPR equipped airplanes will be based on this analysis.
We will revise the Operations Manual Bulletin (OMB) as soon as the analysis is
complete to advise operators of the results of the testing and the final
recommendations about block maneuvering speeds.
56. Revised 737 simulator data promised 6 months ago - when will it be available?
<ANSWER> The following dates are planned for the availability of updated simulator
software with full rudder side slip data: 737-200 - 11 Jun 99, 737-300 - 30
Apr 99, 737-400 - 27 Aug 99, 737-500 - 30 Jul 99.
57. How does the pilot decelerate with the new speeds bumping up against flap placard
speeds?
<ANSWER> There should be no significant impact to flap placard speeds when applying the
increased maneuver speeds to normal landing weights. There is a 30 to 40 knot
difference between the flaps 1 placard of 230 knots
(-200,-300,-500) or 250 knots (-400) and the revised speeds of 200 kts and
210 kts respectively. In the event of an inflight malfunction, we recommend
following speeds defined by the non-normal checklist and not following the
revised maneuvering speeds.
58. Will these new speeds cause the airplane to go to Category “D” circling minimums?
<ANSWER> Circling minimums depend on the speed the operator uses to fly the circling
approach. Most approach charts are published today with these speed
dependent minimums in a matrix titled, CIRCLE-TO-LAND. When flying a
circling approach, the pilots must enter the matrix at the actual circling speed to
determine the appropriate minimums. It is interesting to note that the “C” and
“D” categories have different speeds in different parts of the world.
59. Are the new speeds law or a Boeing recommendation?
<ANSWER> The revised maneuvering speeds are a Boeing recommendation in compliance
with the FAA recommendations published in Flight Standards Information
Bulletin, FSAT 99-02.
60. Are the flap maneuver speeds in the AFM?
<ANSWER> Minimum flap maneuvering speeds are not published in the AFM. However, the
block maneuver speeds are contained in the Flap Retraction Schedule, found in
the Performance section (Sec. 4) of the AFM. See question #51 for a
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discussion of the effects of revised maneuvering speeds on the Flap Retraction
Schedule.
61. Can operators who use amber band +20 knots for flap maneuvering speeds on 737
“classic” airplanes modify their procedure to amber band +30 to 40 knots to meet the
requirements of the “revised maneuver speeds” guidelines?
<ANSWER> An operator can use this technique to comply with the revised maneuvering
speeds contained in 737 Information Bulletin 99-1 by adding 40 kts to the
amber band speed.
62. For rudder hardovers, why not change flap setting instead of increasing speed?
<ANSWER> As per the Boeing Uncommanded Yaw or Roll procedure, decreasing pitch
attitude and increasing airspeed is the most effective means of upset recovery.
Boeing does not recommend configuration changes during upset recovery.
63. Have we looked at the impact the revised maneuver speeds will have on noise limits?
<ANSWER> Unfortunately, noise restrictions may be affected when using the revised block
speeds. We would encourage operators who are confronted with this concern
to consider installing the RPR at their earliest convenience. As soon as Boeing
engineering completes the analysis of RPR flight test data, we will advise
operators about returning to the use of original block maneuvering speeds.
64. Won’t the new block maneuvering speeds increase wear on hardware?
<ANSWER> We do not believe hardware will be affected since the revised speeds will be
primarily be applied at normal landing weights. See question # 56.
65. Does Boeing have the RPR kits available?
<ANSWER> Yes, digital Yaw Damper Coupler (DYDC) and Rudder Pressure Reducer
(RPR) kits are available now. Arrangements for procurement can be made via
Boeing Spares.
66. Will these revised speeds affect the Performance Engineer’s Manual (PEM)?
<ANSWER> Since these revised speeds are temporary until the RPR is installed, they will not
affect the PEM.
67. Can airlines get the aero chart showing crossover speeds?
<ANSWER> Yes, charts showing maneuvering speed versus the crossover speed are being
prepared for distribution. This information should be available in the very near
future. We will disseminate this information to all 737 operators by one of
Boeing's normal communications channels when available.
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68. If center of gravity (CG) is not considered, can we use the original block maneuvering
speeds?
<ANSWER> Although CG does affect the crossover speed, weight is also a factor.
Eliminating CG considerations does not remove the need for the revised
maneuver speeds.
69. When airplane is dispatched with RPR inoperative or the RPR fails to return to normal
pressure, do you return to the higher revised maneuver speeds?
<ANSWER> We will address this issue when the Operations Manual Bulletin (OMB) is
reissued after RPR test results are available.
70. Why didn’t Boeing use a separate light to indicate an RPR failure?
<ANSWER> The A-System Flight-Controls Low-Pressure Light was chosen to annunciate
certain failures of the RPR system because it met the requirements for providing
crew awareness without adding a new indication and therefore a new crew
procedure to the flight deck.
71. What’s the effect of a radio altimeter failure on the RPR?
<ANSWER> The RPR is electrically controlled by the Digital Yaw Damper coupler (DYDC).
On single radio altimeter (RA) installations, the RPR returns to normal pressure
with the loss of the RA. If two RAs are installed, the DYDC will average the
reported altitudes if they differ by a small amount. If RA differences are large,
the DYDC will not use the altitudes and the RPR will remain at full pressure. If
one RA is inoperative, the DYDC will use the other RA. If both RAs are
inoperative, the RPR will return to normal pressure.
72. Has the JAA accepted these new maneuver speeds?
<ANSWER> Boeing has not reviewed the revised maneuvering speeds with the JAA. Boeing
is not aware of any “official” JAA position regarding the revised maneuvering
speeds.
73. Will the 737 simulators operated by Flight Safety Boeing (FSB) be brought up to date
and include the non-normals to allow training in Jammed/Hardover Rudder events and
Unusual Attitude Training?
<ANSWER> Once the RPR Flight Test data analysis has been completed by Boeing
engineering, 737-200/300/400/500 simulator aero data will be updated to
reflect new full rudder side slip effects. This data will be available to all
operators. The FSB simulators will be upgraded with this new software.
FSB does not intend to train a specific rudder hardover event but will provide
Upset Recovery Training as part of recurrent training. Since an upset is much
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more likely to be caused by a problem other than a full rudder hardover, we
believe training the upset recovery technique regardless of the reason for the
upset is more important than training to a specific malfunction. The preamble to
the Uncommanded Yaw and Roll non-normal procedure found in both the 737
AFM and QRH was written to provide general guidance for recovering from
any event that upsets the airplane. The upset recovery technique as defined by
the Airplane Upset Training Aid released in Oct 1998, provides more detailed
recovery techniques that an operator can use to develop upset recovery
training.
If an operator desires to train the Jammed or Restricted Rudder non-normal
checklist, we believe it should be presented not as an upset event but to ensure
pilots understand the reason for each step and are trained to follow the steps
carefully and accurately.
MISCELLANOUS
74. Is the 737 Flight Crew Training Manual (FCTM) available in a digital format? Is it
possible to get the FCTM on CD-ROM?
<ANSWER> Yes, the FCTM is available on a CD-ROM. It comes in 3 different formats. If
your airline receives 5 or less paper copies of the FCTM there is no charge for
the CD-ROM. If you receive more than 5 copies, there is a charge. To order a
CD-ROM, contact Boeing Flight Technical Publications at (206) 662-7700
(ph) or (206) 662-7812 (fax).
75. Does the term “turbulence penetration speed” mean a “maximum” or “recommended”
turbulence penetration speed?
<ANSWER> Recommended. The turbulent air penetration speed must be at least 35 kts
below Vmo/Mmo for structural loads requirements. In addition, for
maneuverability, the speed must be above minimum maneuvering speed.
Therefore, the recommended turbulent air penetration speed is between these
two requirements. The recommended turbulent air penetration speed is the
speed which provides the greatest margin to initial buffet unless the requirement
to be 35 kts below Vmo/Mmo forces it lower.
76. Why is no consideration given to the use of VNAV, geometrical vertical path angles
coded in the navigation database?
<ANSWER> Prior to U7.1, vertical angles from the data base were not used by the FMC to
calculate the VNAV path, since VNAV disconnected when flaps were
extended beyond 15 degrees, and VNAV was not certified for approach
operations. Beginning with U7.1, navigation data base vertical angles are
included in VNAV descent path construction if coded by the navigation data
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Seattle, Washington
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base supplier. The vertical angle is flown into the waypoint, which is typically the
runway for approaches. Since the angle is flown into the waypoint, there may be
a short level segment after the FAF, until the vertical angle is intercepted. On
U7.1 and later FMCs, VNAV is certified for approach operations and remains
valid for all flap settings. Boeing is currently in the process of developing a nonprecision
approach procedure which will utilize VNAV to track these vertical
path angles for the 737NG. Boeing Flight Operations SyBoeing Flight Operations Symposiummposium
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