飞行员操作飞行手册Pilot Operational Flying Manual

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passengers will be competent

professionals in their own field and

will be used to helicopters, probably

flying with several companies aside

from yours. All they will be

interested in is safe transport, so give

them a smooth flight and a good

briefing. Word gets around.

Avalanche Control

This involves applying explosive

charges to selected places in an

avalanche start zone, so you need

permission to carry Dangerous

Goods. You must be precise, and

there will be a qualified Blaster

(Bombardier) on board to dispense

the explosives, who will have a body

harness secured to the helicopter in

two places – it must not have a

quick-release mechanism. The doors

will be off, so you need to dress

properly and watch your speeds and

C of G, especially lateral. In fact, the

weight of explosives and people

required for the job must not be

more than 75% of the useful

payload. Ski baskets, or any other

restrictions to dropping must be

removed beforehand.

The area should naturally be closed.

Primers must be prepared before

entering the aircraft and pull-wires

carried separately – none are to be

adjusted inside, and they are to

remain in the same container at all

times. Only the explosives to be

used on a particular sector should be

carried, and they must be pushed

away from the bombardier’s seat

Special Use Of Aircraft 243

position where you can see them,

not above, behind or below. You

have 90 seconds after dropping the

first bomb to do the rest before you

must pull away to a safe area for

observation. If there is no assistant,

that is, just you and the bombardier

are on board, you can only drop

three charges anyway.

Aerial Harvesting

Removing tree crowns or cones

from standing trees with a

helicopter, for monitoring the

progress of growth, insect or disease

infestation, and pesticide or fertiliser

trails. There are two ways of doing it.

The first involves an unmanned

device underneath the machine

which uses the downwash to

separate foliage from the tree, which

ends up in the device. A Branch

Collector cuts branches from the main

stem, a Rake collects cones by

stripping them from the foliage with

stationary or moving tines, and a Top

Collector takes away the upper portion

of the tree crown.

The second is really aerial clipping,

since it is done by someone from the

rear door with an battery-powered

electric chainsaw while you hover

near the top of the tree. Whatever is

cut ends up in the helicopter, so

there is a barrier between the two

parts of the cabin so you don’t get a

bump on the head. Believe it or not,

this was originally done with a steel

box with retractable doors, the edges

of which cut the tree as the box was

lifted up from it, but it proved to be

slow and cumbersome, and strained

the equipment too much.

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As well as the clipper, there is a

navigator to tell you where to fly,

since you will be busy enough at that

level. Don’t expect to fly more than

6 hours a day, or in wind over 15 kts.

The aircraft itself must be on low

skids, with no bear paws, or items

that can get caught. You yourself

must be an ace at long-lining, with at

least 1000 hours on type.

You start off with a hover

somewhere between 25-50 feet

above the trees concerned, using up

to 85% torque, so you’ve got a

reserve. Keep them between your

right shoulder and just forward of

the front edge of the front door.

Then descend to within eye level of

the target, always being aware that

trees sway in the wind and you can

either get hit by another or hit

something else as you try and keep

up with the tree you are working

with (your downwash won’t be

helping). Its top should be level with

your eyes or the cabin roof, slightly

forward of your right shoulder.

Don’t fixate on the tree top, but

something else that isn’t moving.

Slide the skid in between the

branches until the stem of the tree is

against it, using a little collective just

before contact. Then lower the

collective so the skid rests against

the lower branches to keep it steady

for the clipper, who shouldn’t take

more than a minute to do what’s

required. Before you move away,

check the skid isn’t caught on

anything, then increase collective

and use left cyclic to pull you away

gently. Don’t move directly

sideways, as upwards slanting

branches near the tops of trees could

snag you.

A couple of points to watch – if you

bend a tree beyond the cyclic stops,

when it rebounds you will be out of

limits as you try to correct things.

244 Operational Flying

You will do best to keep level and

use left cyclic with the rebound.

Don’t go straight up or you might

get dynamic rollover. Trees with

bent tops indicate heavy crops and

should be avoided, because they will

have too much momentum. If you

have to work round a tree top, hover

away and assume a new position

every time rather than spinning

round it.

Wildlife Capture

Normally done with a pilot and

gunner (who has a net gun), but

there may also be an assistant (called

a mugger) as well. If there isn’t, and

you have to do the job instead, you

should only handle the head of the

animal, so you don’t get injured

unnecessarily. Your briefing should

include getting in and out of the

helicopter whilst in the hover.

A slightly forward C of G is

preferable. Keeping the rotor disc as

flat as possible, and avoiding tight

turns, approach the animal from

behind, slightly away from the skid

and forward of the gunner, almost

definitely with a sideslip. Don’t

fixate on the animal, but keep it in

view with peripheral vision. The

reason for the flat disc is to keep it

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out of the line of fire, and high-G

turns will upset the gunner’s aim.

Sometimes the wildlife will be seals,

so you have to wear lifejackets and

stuff, and dodge the waves when

they get a bit big (sometimes you

have to use the waves to get you

back in the air again).

Helicopter Instrument Flying

This is much the same as for fixed

wing, but there are a couple of

differences worth noting. Firstly,

thrust and lift come from the same

source, that is, the main rotors, so

you can have different attitudes than

expected when climbing, descending,

or in level flight, so you need to

learn particular power settings for

particular stages of flight to do it

correctly. These, of course, are

controlled by the collective and

displayed on the torquemeter. The

AI indicates fuselage and not disc attitude,

so does not always tell you what the

aircraft is actually doing – you could

be nose-up and still descending at 60

kts, so more cross-checking with

other instruments is required than

with a fixed wing aircraft. Put

another way, while it is still

important, the AI loses a little of its

distinction.

Also, the ability to fly at low speed,

say, below 60 kts, means that the

pitot-static instruments become less

reliable. You also get reduced

stability, which is why there is a

minimum IMC control speed (Vmini),

below which you shouldn’t go into

cloud, as well as minimum speeds

with one engine out, should you

have two.

Having said that, the attitude + power

= performance equation is still valid.

Techie Stuff

An Ops Manual, despite the

adoption of the Flight Manual as

part of its structure, will need a

Technical Section dealing with

aspects peculiar to the Company's

types of aircraft (that is, Part B). You

may feel you've been taught enough

of it already, but things like oil and

fuel requirements and specimen

performance data will still need to be

emphasised. Also, the checklists in

the usual standard of Owner's

Manual are nowhere near good

enough for Commercial Air

Transport, so these will need to be

expanded, too (they never seem to

grasp the idea of battery saving, as

the Master Switch is often the first

thing to be switched on and left on

for the next 10 minutes while you

check everything before starting an

engine).

Whilst not too much information

should be duplicated between the

Flight and Operations Manuals,

enough ought to be included that

may be relevant in flight with

anything of a detailed descriptive

nature left in the Flight Manual. This

is important in smaller aircraft with

no room for a complete library.

Topics to be covered include

crosswind take-offs on ice covered

runways, action not included in

checklists or drills, special handling

techniques and other stuff that needs

to be brought to your attention. Try

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placing emergency drills on different

coloured pages.

If you haven't thought of it already

(because most pilots tend to be

mechanically-minded), it will be well

worth your while digging a little

deeper into engineering principles

and practice in general. Not only will

it help you stay alive, but you get

more out of engineers when you

speak their language. Having said

that, engineers speak in a very

precise manner—to give you a

flavour, try reducing the description

of a piston to just three words (one

suggestion is a sliding, gastight plug).

Just for fun, here is a selection of

replies to pilots’ comments on

returning from test flights in the

USA. They are known as SQUARKS

246 Operational Flying

and are left for maintenance crews to

sort out before the next flight.

Test flight ok, except auto land a

bit rough

Auto land not installed on this aircraft

DME Volume unbelievably loud

Volume set to a more believable level

Friction locks cause throttle levers

to stick

That's what they are there for

Number 3 engine missing

Engine found on right wing after brief

search

Target radar hums

Reprogrammed Target radar with the

words

Aircraft handles funny

Aircraft warned to straighten up and be

serious

Left inside main tyre almost needs

changing

Almost replaced left inside main tyre

Evidences of leak on right mail

landing gear

Evidence removed

IFF inoperative

IFF always inoperative in OFF mode

Something loose in cockpit

Something tightened in cockpit.

Leading Edge Protective Tape

Protective tape is used on leading

edges of rotor blades (and some

propellers) to protect against wear

and tear from dust or precipitation.

A partial loss of it can dramatically

affect aerodynamic efficiency,

resulting in substantial increases in

power when hovering. It will also

cause a slight loss in RPM during

autorotation.

The most likely time for the stuff to

come off is during or after flight

through rain, which is just when it's

needed, so check it before take-off.

If it looks like wearing out, remove

or repair it before the next flight,

removing an equivalent amount

from each blade, as it may have also

been used for balancing. It will be

put on in short strips of anything

between 6-18 inches (so you're not

flying with a great length of it

hanging off) which should be

removed as a whole—don't just cut

bits away.

If tape comes off in flight (with a

distinctive "chuffing" sound,

sometimes accompanied by vertical

bounce), reduce power and speed

and make gentle manoeuvres while

landing. If it comes off before

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landing, just carry on.

Propeller Overspeed

If engine control is lost and RPM

rises above the maximum, reduce

power, raise the nose and hope

reduced airspeed gets things under

control. If the CSU is not working,

feathering immediately may leave

you with a shut down engine in fully

fine pitch, though it does depend on

the aircraft (Doves, apparently, have

a separate feathering motor).

If you're not quick enough, damage

could be caused from over-revving

and the feathering system may not

cope with the extreme RPM. DO

NOT attempt to unfeather the

engine but land as soon as possible.

Techie Stuff 247

Failure of Feathering System

Most feathering systems don't

function below a certain low RPM

(typically 700-1000), so you don't

start with the blades feathered.

However, there are further

implications—if your engine fails

through a major mechanical fault,

you may not be able to catch the

propeller quickly enough. The usual

reaction is to close the throttle of the

dead engine first, so opening it a

little may increase the RPM for

feathering to take place properly.

Keeping your speed up may help as

well.

If the propeller fails to feather,

reduce your airspeed to a minimum

(but not below scheduled engine-out

climb speed) and allow the RPM to

stabilise as low as possible. Try

again. If feathering still fails, try to

reduce speed so the rotation ceases,

which will cause less of a drag

penalty than a windmilling prop,

even if it has stopped in fine pitch.

Not only will your single-engined

climbout performance be affected,

directional controllability will be,

too, though you should be OK

down to Vmca.

Twins

Flying twin-engined helicopters

requires a different philosophy in

many ways, certainly getting used to

not dumping the collective every

time an emergency happens, and

their complexity, although there is

no real change in flying

characteristics as there would be if

an engine fails in an aeroplane. You

also have takeoff and landing

profiles, in case something happens,

and performance charts, with

generally more shallow approaches

to comply with them.

The regulations require you to

ensure that your aircraft has

adequate performance for any

proposed flight. The "performance"

of an aircraft describes its ability to

maintain certain rates of climb

against distance, so you can avoid

hard objects (obstacles), particularly

when you can't see them. As a result,

the charts will emphasise rates and

angles of climb very strongly (climb

requirements are established with

one engine working hard for a

specified time).

There are reasons for multiple

engines, of course. One is that you

get more power and can lift more,

but another is for safety – failure of

an engine should not affect the

continued safe operation of the

flight, or the other one, which is why

there are isolation arrangements in

the engine compartment. It follows,

therefore, that the less the weight of

the machine, the better it can fly

with less power. In fact, with

reference to the profiles above, you

may find different max all-up

weights for helipads and clear areas

(there is no definition of a "helipad"

for performance purposes – rather,

it's any area that isn't a clear area, or

one that allows operation inside your

chosen performance group).

The take-off and landing phases of

any flight are the most critical,

demanding the highest skills from

crews and placing the most strain on

the machine. Because of this, strict

regulations govern the information

used for calculating take-off or

landing performance. Of course, in

the old days (say during the war, or

when the trains ran on time), having

248 Operational Flying

enough engines to lift the load was

all that mattered and no priority was

given to reserves of power and the

like. Now it's different, and you must

be able to keep your machine a

specified distance away from

obstacles and be able to either fly

away or land without damage to

people or property (and the

machine) if an engine fails.

Performance requirements will be

worked out before a C of A is

issued, over a wide range of

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conditions. They are subsequently

incorporated in the Flight Manual,

which forms part of the C of A.

Helicopters are certified in one of

several groups. For example, JAR

classifications are 1, 2 and 3, which

are broadly equivalent to the UK

Groups A, A(Restricted) and B (see

the table below). It is important to

realise that these are different from

Airworthiness groups, which dictate

how well the airframe stands up to a

forced landing.

Passengers JAR Class UK AN(G)R

Over 19 1 A

9-19 2 A (Rest)*

Less than 9 3 B**

*Up to 15 passengers and 12,500 lbs

** Less than 6,000 lbs

JAR Class 1 (Group A) helicopters

require no forced landing provisions

if an engine fails. Class 2 machines

have a limited exposure (that is,

occupants and third parties must

remain uninjured), while Class 3

types have to make a forced landing.

Single-engined helicopters therefore

come under Class 3. In addition,

Class 2 ops must be done under

conditions that allow a safe forced

landing, in terms of weather, light

and terrain – those done from

elevated pads in non-hostile

conditions must be done by day

only, otherwise you must abide by

Class 1. Class 3 ops must be done in

sight of the surface, by day, with at

least a 600-foot ceiling. The

minimum visibility is 800m.

The screen height for JARs is 35

feet, for takeoff and landing. There

are no distance requirements.

Group A helicopters must (with one

engine out) clear all obstacles under

the departure track within a defined

area by a specified margin. In fact,

they should be able to climb (after

CDP) at 100 fpm to MSA with the

gear down (most unfavourable C of

G), then continue at 150 fpm to

MEA with One Engine Inoperative

(OEI). Naturally, if the remaining

working engine is not powerful

enough to lift the weight, the flight

will not continue, so, as with fixed

wing, there is a point during the

takeoff procedure at which, if an

emergency happens, you elect to

carry on or reject, called,

unsurprisingly, the Critical Decision

Point, or CDP, which is the only

point at which you have two choices.

Which group you belong to depends

on Certification, Max All-Up Weight

and the number of passengers

carried, although the JAR

classifications are based on the latter

(see below). However, it may be

more acceptable commercially to

operate in a lesser group if it enables

you to take more payload, and make

more money – all you might need is

longer takeoff runs or less obstacles.

In other words (just to reinforce the

point), the conditions under which

Techie Stuff 249

you operate determine how heavy

your aircraft can be and, as a result,

your payload. Over a whole trip, the

weight could be dictated by:

· Maximum weight

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· WAT limits (see below)

· Space available

· Obstacles

· The route

· Hovering OGE

Individual machine performance will

vary due to such variables as the age

of the airframe and engines, the

standard of maintenance, or crew

skill and experience, without the

engines being adjusted for several

seconds after the initial failure. What

you can do on one day under a given

set of circumstances may well be

impossible another time.

Performance is therefore a set of

average values—particular machines

may be better or worse.

The original testing, of course, is

done with new aircraft and

experienced pilots, which are known

as unfactored. Fudge factors are

applied to unfactored figures to

produce net performance (and gross

performance when they're not), so

there is a margin if you have a tired

engine, or a new pilot. Occasionally,

performance data (as amended) in a

flight manual will already be

factored, but you will have to check

the small print on the chart, in case

they surprise you (JAR does not

make a distinction between the two,

except for a 1% margin for IFR).

Also, figures and graphs are based

on Standard conditions which allow

for fixed reductions in pressure and

temperature with height. As we all

know, the real world isn't like that,

so these assumptions may not always

be true and due allowance must

therefore be made for them (if your

aircraft is performing sluggishly, you

may find it's not the machine, but

the conditions it has to work under

that are at fault).

Profiles

A profile is a series of target steps to

be achieved on takeoff or landing,

designed to give you the best chance

in an emergency. For example, with

a TwinStar in a clear area, you would

go up to 6 feet, then nose forward to

10 feet and 30 knots, (CDP)

accelerate to 40 kts (VTOSS) up to 550

feet, level out and accelerate to 55

kts (VY):

In practice, with both engines

performing normally, you would

accelerate as quickly as possible

through CDP and climb away as you

would with a single – only if an

engine fails would you decelerate to

VTOSS, or Takeoff Safety Speed (the

equivalent to V2 in a plane, for the

best angle of climb, then adopt VY at

the prescribed height, for the best

rate of climb.

The CDP is the only point where

you have a choice of action – before

then, you reject. Afterwards, you

carry on. The LDP is a similar point

for landing, where the idea is to hit a

speed and height combination from

where you can make an approach

250 Operational Flying

that will allow you to land safely

(most people get to one first, then

creep up on the other).

There can be many variations on the

Cat A theme:

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· Airfield, or Clear Area, with

distances around 1000-1500 feet

to play with, accelerating to

where you can climb even at

max weight, usually close to VY.

· Reduced Field Length, climbing

vertically or even backwards, to

land in a much smaller area if

you have to, say 300-500 feet

long, usually at about 85-90%

max weight.

· Vertical, which speaks for itself,

but you may have the option of

a dip below heliport height or

not (i.e. at ground level). The

former allows 90% max wt, the

latter around 80%

Class 1 helipad take-off procedures

involve climbing vertically at first,

then going upwards and backwards

to a predetermined height (the

Critical Decision Point, or CDP) before

going forward (actually, ICAO now

call it the Takeoff Decision Point, or

TDP). This could be up to 150 or

200 feet above the helipad, after

going vertically to about 50 feet first

(if you've got the power on a hot

day!). For the TwinStar, you start

going backwards from about 15 feet,

at around 200 feet per minute,

keeping the helipad in sight, and at

TDP (90 feet) select max power and

10° nose down at the same time, so

your tail doesn't hit anything.

In theory, having moved backwards,

you still have the take-off spot in

sight and it's therefore available for

landing. At CDP (or TDP), if you

elect to carry on to forward flight,

you should be able to clear the

landing spot during the steep dive

you have to make to achieve flying

speed, which is why the CDP is

about 40 feet high. Once you're

happy about the power, gently

accelerate level, to VY.

All this is not without its critics,

though, since prolonged hovering at

high engine power is not necessarily

good engine handling. Not only that,

it may be impractical on an oil rig if

there are accommodation blocks and

cranes around.

Unofficially, therefore (from a rig

anyway), one school of thought

suggests a level acceleration to best

rate of climb speed, then going up to

a safe altitude, whereas others

advocate getting to best angle of

climb speed, climbing to a safe

height and then accelerating to best

rate of climb. The first is supposed

to keep you in the H/V curve less,

but the second gets you higher

sooner, so you lessen the chances of

hitting the water if an engine fails,

especially if the deck is only 50 feet

high (most major platforms are 100

feet off the water).

One technique might be to hover

over to the front of the deck with

the rotors not overhanging (the front

is where the wind is coming from).

Check the Ts & Ps as usual, then

pull power and head upwards,

rotating while there is a positive rate

of climb to a few degrees nose down

(10 is OK initially - you might lose

height with more), to get the tail up

and clear. After rotation, maintain

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the collective while looking for

takeoff safety speed and accelerate.

Techie Stuff 251

As to which technique is best, you

have to make some choices yourself,

like whether you want to hit the

water or the deck, or would rather

be low with rotor RPM, or higher

with less, and little airspeed.

To get back on to the ground, you

will not be surprised to hear there is

a landing profile as well, for the

Twinstar being something like this:

For a clear area, you arrive at the

100' point at 40 kts (it's actually

difficult to get them both at the

same time, so you would first hit

one, then the other). For a helipad

(that is, not within the definition of a

clear area), the figures are 90' and 30

kts, for a semi-vertical arrival.

Factors Affecting Performance

Density Altitude

This is the altitude at which the ISA

density is the same as that of the air

in question or, in other words, your

real altitude resulting from the

effects of height, temperature,

pressure and humidity, all of which

can make the air thinner and which

are mentioned below. The details

will be in the Flight Manual,

although humidity is usually ignored

in the average performance chart,

because it has more to do with

engine power than aerodynamic

efficiency, and high air density and

humidity do not often go hand in

hand. However, if the air is humid,

say after a good shower, you would

be wise to be careful.

Anyhow, the idea is that the more

the density of the air decreases for

any reason, the higher your aircraft

thinks it is. If you look at the lift

formula, you will see that the lift

from a wing or thrust from a

propeller is directly dependent on air

density, as is drag, of course. The

effects are as valid at sea level as they

are in mountainous areas when

temperatures are high – for example,

90° (F) at sea level is really 1900' as

far as your machine is concerned. In

extreme circumstances, you may

have to restrict your operations to

early morning or late afternoon.

Here is a handy chart:

°F/C 60/15.6 70/21.1 80/26.7

1,000’ 1300 2000 2700

2000’ 2350 3100 3800

3000’ 3600 4300 5000

4000’ 4650 5600 6300

5000’ 6350 6900 7600

6000’ 7400 8100 8800

7000’ 8600 9300 1,0000

8000’ 9700 10400 11100

9000’ 11,000 11600 12400

1,0000’ 12250 13000 13600

11,000’ 13600 14300 15000

12000’ 14750 15400 16000

It shows that, at 6,000 feet and 21°C,

for example, you should enter

performance charts at 8100 feet.

TODR will increase by 10% for each

1000-foot increase in aerodrome

altitude and 10% per 10o C increase

in temperature (factor by 1.1).

252 Operational Flying

LDR will increase by 5% for each

1000-foot increase in pressure

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altitude and 10o C increase in

temperature (factor by 1.05).

Aircraft Weight

Greater mass means slower

acceleration/deceleration and longer

distances. TODR will increase by

20% for each 10% increase in weight

and LDR 10% per 10% increase in

weight (factor by 1.2 and 1.1). Very

few aircraft allow you to fill all the

seats with full fuel.

Some manuals give take-off and

landing weights that should not be

exceeded at specific combinations of

altitude and temperature, thus

ensuring that climb performance is

not compromised. These are known

as WAT limits (Weight, Altitude and

Temperature)

Dynamic Rollover

This occurs when your helicopter

has a tilted thrust vector with respect

to the C of G, commonly

encountered with some side drift

when you have one skid or wheel on

the ground acting as a pivot point,

but you can also get a problem when

your lateral C of G falls outside the

width of the skids or wheels. Every

object has a static rollover angle, to

which it must be tilted for the C of

G to be over the roll point, for most

helicopters being 30-35°. As your

lateral cyclic control at that point is a

lot less effective than if you were

hovering, because it is not rotating

around the C of G, but the rollover

point, you have less chance to get

out of trouble, and the only effective

control is through the collective (do

not raise it). In other words, the lift

from the rotor disc that should be

vertical is inclined and converted

into thrust, above the centre of

gravity, so trying to use the cyclic to

level, and the collective to get you

off the ground is wrong!

Dynamic rollover is worst with the

right skid on the ground (counter

clockwise main rotor) and with a

crosswind from the left, with left

pedal applied and thrust about equal

to the weight (i.e. hovering). A

machine can roll upslope if you

apply too much cyclic into it, or

downslope if you apply too much

collective, enough to make the

upslope skid rise too much for the

cyclic to control. Avoid it by keeping

away from tail winds, and landing

and taking off vertically.

Engine Failure and

Autorotations

This part is not meant to cover

(again) the basic stuff you learn in

flying training, but to offer advice

that would be useful to a working

pilot, who is very often over trees, or

in remote places that the student is

routinely taught to avoid. In short, it

talks about surviving a potential

crash, because you won't always find

yourself over the clear areas you

need for training.

Engine failure in a helicopter is

detected by a noticeable decrease in

engine noise (!), yaw in the same

direction as blade rotation, loss in

height/speed and RPMs, plus

ENGINE OUT audio/visual

warnings (if fitted), because there's

so much noise you can't tell whether