CFM Oil Temperature Sensor Issue

航空

游客，如果您要查看本帖隐藏内容请回复

航空

February 2002 WTT face to face CFMI / Boeing Proprietary Information - Unauthorized Disclosure, Use, or Export are Prohibited 1
Oil Temperature Sensor Issue
February 2002 WTT face to face CFMI / Boeing Proprietary Information - Unauthorized Disclosure, Use, or Export are Prohibited 2
Oil Temperature Sensor Issue
Components & Accessories
Background
• Five commanded IFSD’s following Low Oil Pressure Warning / Low Oil Qty
• Ground inspection showed oil temperature sensor separated from housing
– All the oil expelled from the open port
• Event engines age less than 850 cycles since new
• Events led to extensive engine damages (bearings failure)
– Low oil pressure warning delayed due to invalid PEO
February 2002 WTT face to face CFMI / Boeing Proprietary Information - Unauthorized Disclosure, Use, or Export are Prohibited 3
Root Cause
• TEO Sensor with attachment bolts and self locking inserts disengaged all
together and holes threads in housing found sheared
• Insert over torqued during assembly (or maintenance)  damage to the
insert
– Engine oil pressure cyclic load on the probe  shearing of the
insert threads and to back off the probe
– lack of robustness of the insert design  sensitive to over torque
Insert
Bolt
Sheared
threads
Root Cause Understood = Insert Sensitive to Over Torque
Oil Temperature Sensor Issue
Components & Accessories
February 2002 WTT face to face CFMI / Boeing Proprietary Information - Unauthorized Disclosure, Use, or Export are Prohibited 4
Production Final Fix
• Mechanical Fix
 A new housing design, more robust, new insert definition has been
implemented
– With this new insert, six (6) threads are engaged instead of three (3) on
the current housing.
– The bolt becomes the weak link in this assembly (demonstrated by test)
– On new production engines since May 2001 (engine 88T-481 and up)
 SB 72-0298 issued 5 Jul 2001
• Software Fix
 Lower limit for PEO signals reduced to ensure low oil pressure warning
activated in worst case scenario (sudden oil supply line open to ambient)
– Introduced in 7BM1 software (1853M79P20) - S/B 73-0064, 31 Jul 2001
Oil Temperature Sensor Issue
Components & Accessories
February 2002 WTT face to face CFMI / Boeing Proprietary Information - Unauthorized Disclosure, Use, or Export are Prohibited 5
In-Service Plan
• Containment Plan
 CFM recommended Implementation of lockwire
between probe and housing for engines having
accumulated less than 1,000 cycles since new, or for
those on which a maintenance action on the TEO
Sensor had been performed
– S/B 72-A0336 issued on 26 Jun 2001
 CFM recommend implementation of lockwire on all
field engines regardless of age
– S/B 72-A0336 to be revised
 Target date Mar 2002
Oil Temperature Sensor Issue
Components & Accessories
February 2002 WTT face to face CFMI / Boeing Proprietary Information - Unauthorized Disclosure, Use, or Export are Prohibited 6
In-service Final Fix Plan
 CFM recommends mechanical final fix implementation during engine
shop visit to replace the interim fix
– This can be done by
 Installation of the new housing configuration (P/N 805) with
longer inserts
 Installation of a current/reworked housing (P/N 804 -> P/N TBD)
» Valid for a non damaged housing
» Rework to be released in Mar 2002
» S/B 72-A0336 to be revised in Mar 2002
Oil Temperature Sensor Issue
Components & Accessories

979199501

Arm Proposed Switch Configuration Current Double Throw Proposed Single Throw Run contact eliminated Introduction Logistics • CFMI/Boeing/Honeywell laun

kinran

bocome

CFM Oil Temperature Sensor Issue