Fixed Wing

Panel Foreign Object Damage

BOEING, 737 8CT
SERVICE DIFFICULTY REPORT
(SDR) # 20111011011

SDR submitted:

The aeroplane returned to the gate due to loud feedback on the captain’s audio channel and a report of electrical smell. Maintenance confirmed that the captain’s audio selector panel (ASP) failed, causing the electrical smell. The defect was resolved through the replacement of the ASP and tested as per Aircraft Maintenance Manual 23-50-00.

Damaged audio selector panel circuit board

* Blobs of solder
**   screw
***   U401
****
 
Damaged audio selector panel circuit board

Transport Canada Comments:
Feedback from the operator through the ASPs shop teardown report confirmed its failure due to foreign object damage (FOD) where a dislodged screw was found within the unit, causing a short.

It is suspected that while the aeroplane was in operation, a screw was inadvertently dropped into the ASP, causing the
eventual failure of the unit.

Transport Canada Civil Aviation would like to advise all operators and maintainers of the dangers of FOD.

Elevator Trim Cables Twisted

BAE - UK, 3112
SDR # 20111011015

SDR submitted:

During a maintenance inspection of the rudder trim tab control system, it was noted that the rudder trim cables were crossed in the leading edge of the rudder above the lower leading edge panel.

This area is very difficult to inspect due to the access and no available inspection panels on the rudder leading edge.

Both cables were replaced due to minor kinks noted and installed correctly as per Aircraft Maintenance Manual (AMM) 27-23-11.

Rudder trim cable run for the aft fuselage

* Cable run area most prone to possible cable cross-over
** Rudder trim cable run for the aft fuselage and empennage area

Transport Canada Comments:
The Aircraft Maintenance Engineer, through consultation with other operators, has confirmed several other similar occurrences where it has been stated that rudder cable cross-over in the vertical stab is a known problem and “it is easy to do”.

Transport Canada Civil Aviation is advising all BAE 3112 operators and maintainers of the possibility for the
elevator trim cables to be twisted and to follow the AMM 27-23-11 procedures closely.

Integrated Drive Generator Oil Leak

BOEING, 767 375
SDR # 20111026011

SDR submitted:

The flight crew disconnected the left Integrated Drive Generator (IDG) approximately 3 hours into the flight due to the drive light and Engine Indication and Crew Alerting System (EICAS) message illuminating. Maintenance discovered two adjustment bolt heads missing and oil in the cowl.

Oil is believed to have escaped under pressure past the broken bolt heads.

The IDG was replaced and the aeroplane was made serviceable.

Missing bolt heads and oil leak path

* Missing bolt heads and oil leak path

Transport Canada Comments:
The operator has only seen this issue once before in 1999. The suspected issue is the stator and housing clearance wearing over time. As the clearance increases, the load being applied to the IDG makes the stator try to turn inside the unit due to the magnetic field and the rotation of the rotor (1200 rpm). The stator moves more and more as the wear on the bolt holes increase (elongation of the holes is evident on the housing).

A large load or electrical demand and the sudden movement of the stator are suspected for the shearing of the bolts.

Transport Canada Civil Aviation would like to advise all aircraft maintainers of the possible inherent wear characteristics for this style of electrical generator.

Main Landing Gear Side-stay Broken Tension Spring

BOMBARDIER, CL600 2D15 (705)
SDR # 20111123001

SDR submitted:

It was during a service check walk-around inspection when maintenance found a broken left-hand main landing gear side-stay lower tension spring.

The tension spring was replaced and the aeroplane was made serviceable.

Main landing gear side-stay

* Main landing gear side-stay broken lower tension spring

Transport Canada Comments:
The standard walk-around inspection for any aircraft is the most widely used inspection task in aviation. Often enough, it is also the last inspection task done before flight and because of this it is considered an essential task for the continued safe operation of the aircraft.

Nose Landing Gear Drag Brace Spring Failure

BOMBARDIER, CL600 2B19 (RJ100)
SDR # 20111121004

SDR submitted:

On a pre-flight first flight of the day walk-around check, it was noticed that on the nose landing gear, the right hand drag brace spring was broken and hanging.

The discrepant spring was replaced and the aeroplane was made serviceable.

CRJ 200 nose landing gear

* CRJ 200 nose landing gear drag brace spring failure

Transport Canada Comments:
The function of the drag brace gear spring is to assist the operation of the drag brace assembly towards its over-center, down-locked position.

The failure of a spring may lead to a possible inability to safely over-center the drag brace and down-lock the gear.

Transport Canada Civil Aviation would like to advise all owners, operators and maintainers to pay close attention to the condition of these springs.

Forward Fuselage Skin Crack

BOMBARDIER, CL600 2B19 (RJ100)
SDR # 20111005007

SDR submitted:

During a scheduled in-house task for a scratch and dent survey of the external fuselage, the Aircraft Maintenance Engineer noticed a crack emanating from the aft latch cut-out of the left hand electronics bay door at the nose of the aeroplane.

The crack was located at Fuselage Station 189, water-line 75.25 just below the Reduced Vertical Separation Minimum (RVSM) critical area. The damage was reported to Bombardier where the aeroplane was returned to service in accordance with temporary disposition Repair Engineering Order (REO) 601R-53-11-2189.

Forward fuselage station 189, aircraft nose area

* RVSM Lower Edge
** 0.460”
*** 0.325”
**** 0.265” crack
***** Skin Joggle
****** 4.125”
******* Distance to edge of skin at fuselage station 193.00
******** Forward fuselage station 189, aircraft nose area

Transport Canada Comments:
A similar occurrence has been found on another CRJ of the same operator where Bombardier engineering has been notified.

Transport Canada Civil Aviation is advising all CRJ operators and maintainers to be aware of this area for possible crack formations and the available Bombardier repair order.

Worn Propeller Governor Bolt

CANADAIR, CL215 1A10
SDR # 20110915008

SDR submitted:

The bolt that attaches the left hand propeller governor cable fork end to the propeller governor lever was found severely worn part way through the shank of the bolt. This was discovered during a scheduled engine maintenance check. When the lever was wiggled to check for tightness and security, obvious play was noted. The rod end bearing in the lever was solid within the governor arm. The bolt was removed and found worn.

location of worn bolt

* location of worn bolt

bolt showing wear

* bolt showing wear

Transport Canada Comments:
The engineer who carried out the inspection should be commended for discovering this discrepancy. Keep up the good work!

A Near Nose-up Landing Event

CANADAIR, CL600 2A12(601)
SDR # 20110328003

SDR submitted:

During approach after the down selection of the gear, the nose landing gear ("NLG) remained up within its wheel-well. The manual gear release system was selected yet the "NLG remained in its up position.

After several tries to cycle the gear, an emergency landing was declared where it was decided to do a touch-and-go in-order to shake the gear out of its wheel-well. After several tries, it was decided to perform a nose-up landing. Upon touch-down of the main gear, the "NLG went down at the last second prior to the nose of the aeroplane dropping. No incident or injury was reported.

After the landing, maintenance found that the "NLG strut was collapsed and not centered, causing the gravel kit to jam within the "NLG wheel well.

Transport Canada Comments:
Bombardier Service Bulletin (SB) 601-0616 has been released to address the possible scenario where an improperly serviced "NLG strut along with the installation of a “Gravel guard” (post SB 601-0112 configuration), could cause interference and possible jamming of the "NLG.

Corroded Rudder Pedal & Torque Tubes

Cessna 210M
SDR # 20110208018

SDR submitted:

During inspection, the pilots left hand rudder pedal arm, part number (P/N) 0411307, was found loose and severely corroded at the torque tube, P/N 1260465-5. Internal inspection of the mounting arm and stub end of the torque tube revealed severe corrosion in various locations. Two of the four rudder pedal mounting arms showed significant internal corrosion.

Additionally, the interiors of torque tubes, P/N 1260456-5 & 12600456-6, were also found significantly corroded when disassembled. The inboard rudder torque tube bearing blocks were found cracked on both sides.

Pilot and Co-Pilot Rudder Pedal

* Rudder Pedal Torque Tubes
** Cable Attachment Arm
*** Pilot and Co-Pilot Rudder Pedal Torque Tubes and Rudder Cable Attachment Arm

Transport Canada Comments:
The Federal Aviation Authority is aware of the corrosion problems and has advised Transport Canada Civil Aviation that Cessna will soon issue Supplemental Inspection Number (SID) 27-20-01 to verify the integrity of the rudder pedal torque tube assembly. (effectivity 21059062 thru 21059199). Areas of particular concern are rudder torque tubes, cable attachment arms and weld area degradation due to corrosion or fatigue.

Jackscrew – Fuselage Mount

DHC 3T
SDR # 20111003011

SDR submitted:

During a repetitive inspection of the horizontal stabilizer trim jackscrew; it was found that the bottom jackscrew mount was loose and was working into its fuselage-mounting retaining bracket.

Following the removal and disassembly of the fuselage-mounting bracket, it was discovered that three mounting rivets and their associated holes were worn (elongated) causing the bracket to become excessively loose.

A jackscrew mount fitting which is

* A jackscrew mount fitting which is located in rear fuselage tail area

Transport Canada Comments:
This is an area that needs attention during inspections. Should the jackscrew mounting bracket become jeopardized; it could cause an undesirable flutter condition affecting the stabilizer trim flight control system.

Aileron Binding Possibility

EMBRAER, ERJ 190 100 IGW
SDR # 20111026012

SDR submitted:

On taxi out, the flight crews initial test of the ailerons was unusually stiff in both directions. Subsequent movements felt normal and the aeroplane departed with no further issues.

This binding fault occurred on three occasions prior to this event where no fault was found.

Further maintenance investigations revealed a broken bonding strap on the right-hand aileron torque tube located in the right main landing gear wheel-well. These bonding straps have been known to cause the stiff aileron fault and from examination of the area, evidence of the strap having interfered with the bearing support was noted.

It would appear that the bonding strap interfered for a short period of time then broke.

Broken bonding strap and attachment point

* Broken bonding strap and attachment point

Transport Canada Comments:
Embraer have issued Service Newsletter (SNL) 190-27-0009R01, defining this possible scenario with recommendations for the proper installation of the bonding strap to prevent interference.

Light Dimmer Unit Overheat Failure

LEARJET, 55
SDR # 20111114007

SDR submitted:

The co-pilots instrument backlighting system was snagged as inoperative. Maintenance found the co-pilots light dimmer unit switch had failed due to its potentiometer wiper-arm coming into contact with the surrounding wiring behind the instrument panel causing the light dimmer to short out. This in turn caused the potentiometer to overheat, melting the panel and leaving burn marks on thesurrounding wiring.

The wiring was re-secured away from the potentiometer and the switch assembly was replaced.

Light dimmer unit switch assembly view

* Switch wiper-arm short to wiring and panel structure overheat
* Light dimmer unit switch assembly view
from the rear

Transport Canada Comments:
The installation and correct support of wiring is essential to ensure the safe continued operation of all aeroplanes.

Windshield Heat Wiring Short

PILATUS - SW, PC 12 45
SDR # 20111020001

SDR submitted:

During a major inspection of the aeroplane, all cockpit windshields were removed for inspection of associated structure. Upon installation of new windshields, the airframe wire connections for the right-hand heated windshield were too short so were removed from the cockpit overhead run for replacement with new longer wires. Upon removal of the wire loom, one wire # H307/C12 was noted in having a significant burn mark. Further inspection showed a corresponding burn mark in a lightning hole where the wire passed through at frame 15.

The discrepant wire loom was installed 12 years previous as part of Service Bulletin (SB) 30-005, however a braided hose or grommet was not used at the lightning hole as a means of chafe protection defined in the SB. There were no previous reports of windshield heat defects recorded in the log book. The damaged lightning hole was repaired per Structural Repair Manual (SRM) procedures and the wire loom replaced.

Lightening hole electrical short arch damage

* Lightening hole electrical short arch damage

Windshield heat power feed wire chaffing

* Windshield heat power feed wire chaffing and arch damage

Transport Canada Comments:
Correct wire harness support, insulation and protection from chaffing are essential standard practices for the continued operation of an aeroplane. With this case, not only was the defined task for a grommet installation missed during the incorporation of a SB by the Aircraft Maintenance Engineer (AME) responsible, the applicable standard practice was omitted also.

As AMEs, we are all responsible in knowing and following our Instructions for Continuing Airworthiness (ICAs), as with this scenario being the SB and Aircraft Maintenance Manual Standard Practice reference.

Magnetic Chip Detector Unserviceable

ROLLS ROYCE - UK, RB211 TRENT 772B-60
SDR # 20110721007

SDR submitted:

During master magnetic chip detector (MCD) inspection, on removal of the MCD probe, the self sealing valve broke off and fell down the oil tube. The oil tube was removed to recover the parts, the MCD housing was replaced (part number VA3509), the parts were sent to engineering and Rolls Royce was advised.

Swaged cap came off the

* Swaged cap came off the self sealing valve
* Cap is swaged on end of valve

Transport Canada Comments:
Caution is advised whenever disassembling aeroplane components. Thankfully in this case, the broken piece was easily recovered and did not damage another component

Hydraulic Failure

SAAB, SF340A
SDR # 20110602004

SDR submitted:

On climb-out during gear retraction the crew noticed a decrease in the hydraulic pressure while the pump was running with an eventual complete fluid loss. The aeroplane returned to the airport and the landing was uneventful. The cause of the problem was a failed landing gear (LDG) down-lock actuator hydraulic swivel valve. A fitting of the valve had split and allowed the loss of the hydraulic fluid.

The swivel valve was replaced and the aeroplane was made serviceable.

Crack propagation begins here

* Failed Landing Gear Swivel valve fitting
* Crack propagation begins here

Transport Canada Comments:
Through the research of our Service Difficulty Report database via the Web-based Service Difficulty Reporting System (WSDRS), a high failure rate of these swivel valves was noted.

Transport Canada Civil Aviation and SAAB engineering are working together to address this issue and a possible design change is pending for a change of swivel valve material through a Service Bulletin.

All operators and maintainers are asked in the meantime to pay close attention to these LDG swivel valves for hydraulic fluid leaks which could indicate a possible internal crack condition.

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