Fixed Wing

Main Door Harness – Bad Installation & Chaffing

AIRBUS, A330 243
(SDR) # 20120308003

SDR submitted:

At arrival, it was noted that circuit breaker (C/B) 2LW on the cabin overhead panel was out. When the C/B was reset for troubleshooting, significant sparking was noted at the forward right (R1) passenger/crew door. The sparks were concentrated near the main interior door operating handle.  

When the trim was removed from the door, it was noted that the main wire bundle for the door was completely burnt and had arced at one location. It appeared that a grommet was adrift and had split open, allowing a chaffing condition of the harness on the door structure.

Also noted was a missing clamp where a tie-wrap was used to secure the harness, inducing a misalignment condition and eventual harness failure.

The grommet and wires were replaced and a clamp was installed, making the aeroplane serviceable.

Arrows pointing to the missing clamp with tie-wrap being used and harness chaffing/arching condition.

Transport Canada Comments:

Correct installation of any part or assembly of an aeroplane is essential for its continued airworthiness and safety of flight.

Broken Main Landing Gear down-lock assist spring attachment pin.

BOEING, 737 8K5
SDR # 20120305001 

SDR submitted:

During a standard walk-around, the pilot reported that the right hand main landing gear had a loose spring hanging. Upon further investigation it was noted that the right hand down-lock spring attachment pin had sheered and the forward spring assembly had come loose.

The pin was replaced and the aeroplane was returned to service.

Arrow pointing to the right main landing gear broken down-lock spring attachment pin.

Transport Canada Comments: 

The importance of the walk-around inspection from both the flight crew and maintenance engineer is an essential task prior to any flight.

CRJ Fuel Leakage

BOMBARDIER, CL600 2B19 (RJ100)
SDR # 20111209006 

SDR submitted:

The centre fuel tank was fueled to maximum capacity at 2270 kg (5005 pounds). The aeroplane was parked in the hangar and fuel was noted to be dripping from the left-hand aft face of the main landing gear wheel well forward bulkhead just to the left of the aeroplane centerline. Further investigation revealed the leak was coming through the left boost pump electrical connector backshell.

The fuel was entering the wiring conduit because of a cracked flare at the left fuel boost pump canister.

The aeroplane was removed from service and power lockout procedures were immediately carried out. The tube assembly was replaced and all appropriate leak checks were completed, returning the aeroplane back to service.

Fuel boost pump electrical conduit new line and old line with failed flare

Transport Canada Comments:

It is suspected that from past boost-pump canister changes, the electrical conduit B-nut was over-torqued, causing the eventual failure of the conduits flare end.

Transport Canada Civil Aviation is advising all owners, operators and maintainers to reference the Aircraft Maintenance Manual for all required torque values with special consideration when working electrical fuel conduit lines.


Improper Wiring Support

BOMBARDIER, CL600 2B19 (RJ100)
SDR # 20120207004

SDR submitted:

The flight crew reported a passenger door stow caution message on the Engine Indicating Crew Alerting System (EICAS) displays.

Troubleshooting found the main cabin door (MCD) handle proximity sensor (PS1MB) had a frayed and damaged wire from interference with the MCD handle linkage. The proximity sensor was replaced and the aeroplane was made serviceable.

Arrow is pointing to a damaged wire.

Transport Canada Comments:

As defined by the operator, this proximity sensor was recently replaced.

The normal installation and wiring support requires the wires to be bent back 180 degrees against the sensor body and ty-wrapped in place to provide clearance from the inner door linkage mechanisms. It appears that the wires under the ty-wrap migrated back resulting in contact with the handle linkage, causing the damage to the wire.

Wire support failures as defined can generate system failure that can be difficult for maintenance personnel to find and correct.

Transport Canada Civil Aviation (TCCA) is advising all maintenance personnel to adhere to all standard wiring practices and maintenance manual instructions.


Internal Fuel Tank Structural Fatigue

BOMBARDIER, CL600 2B19 (RJ100)
SDR # 20120112001

SDR submitted:

The maintenance technician was performing a internal zonal inspection of the centre wing section as per task card #RJ2-57-900-320 when he found cracks emanating from one of the two relief stringer cutouts for the web of the support angle at both sides of wing station 29.42.

The aeroplane was down for a scheduled “C” check.

New parts were fabricated and heat treated as per Structural Repair Manual (SRM) 51 10 06 section 3D and corrosion protection reapplied as per SRM 51 25 00 and 51 25 16.

: A cracked left-hand collect tank bulkhead angle at wing-station 29.42
: A cracked left-hand collector tank bulkhead angle part number 601R10011-13

Transport Canada Comments:

Transport Canada Civil Aviation (TCCA) is advising all CRJ 100/200 operators to pay close attention to this area in reference to the above mentioned task card for probable crack propagation.


Chaffed wing leading edge harness

BOMBARDIER, CL600 2D15 (705)
SDR # 20120302001

SDR submitted:

During a routine maintenance inspection, chafing was discovered on the spiral electrical cord at each of four locations in the leading edge of the left and right wings (two per side). This spiral electrical cord provides the required electrical inter-connect between the slat and the wing for skew and overheat detection and indication.

The outer harness insulation was worn through and were repaired or replaced as required making the aeroplane serviceable.

Chaffing of spiral electrical cord through to the bare wire
Transport Canada Comments: 

Wire harness chafing such as described in this service difficulty can cause intermittent system failures that can be difficult to trouble-shoot and correct.

Damaged Spoiler Actuator

SDR # 20120229006

SDR submitted:

The pilot noticed during taxi for take-off that the right hand outboard spoiler was not deployed. Upon inspection, hydraulic fluid was found to be leaking from the right hand out board wing. Further investigation revealed a loss of hydraulic fluid at a rate of 1 qt per 10 min of engine operation. Maintenance found the spoiler actuator broken and resulting damage to the mounting bracket at the rear spar. (Actuator damage – threaded portion of end cap cracked 270 degree of circumference)

Actuator with damage highlighted in red box.

Transport Canada Comments: 

This could be a possible area of concern as the fleet ages.


Flap Actuator (Gimbal Assembly)

SDR # 20120430003

SDR submitted:

During a walk-around inspection, it was noted that the left-hand inboard flap segment had an excessive amount of fore and aft movement. Further investigation revealed that the flap actuator gimbal assembly that provides the flap actuator to airframe mounting interface was loose at the flap actuator body.

Upon removal, it was evident the two gimbal retaining pins that hold the gimbal assembly to the actuator body were not properly in place. The lower retaining pin was missing entirely and the upper pin had migrated enough that it was no longer engaged into the flap actuator body. These retaining pins are supposed to be held in place by snap rings; however both snap rings were missing. This led to a condition whereby the flap actuator was no longer secured to the trailing edge of the wing, and was only held in position by the Teleflex cable that operates the flap actuator.

This created a potential for the inboard flap segment to jam or to come entirely free from the aeroplane.

A Gimbal Assembly with a loose pin

Transport Canada Comments: 

Transport Canada is investigating further with the FAA and the responsible Type Certificate Holder.

It is recommended that operators pay particular attention to this area. Flap assemblies are subjected to significant airloads during flight conditions.


#1 Hydraulic Line – Failure

DHC 8 100 series
SDR # 20111215004

SDR submitted:

During descent, the flight crew observed a rapid pressure drop of the #1 hydraulic system which directly affected wing flaps, inboard roll spoilers, normal brakes and anti-skid functionality. An emergency was declared and the aeroplane landed without further incident.

Upon shutdown, maintenance personnel noticed hydraulic fluid dripping from the left hand wheel well. Further troubleshooting revealed that the electrical wires had chaffed into the #1 hydraulic standby pump case drain return tube.

Arrow pointing at the case drain return tube PN 82970009-105.

Transport Canada Comments: 

This is a good reminder to all maintenance personnel to inspect for signs of chafing and fouling conditions at every opportunity when in these confined areas.

In this case, an emergency landing was the result of a fouling condition.


Engine Cowl Latches

SDR # 20120427002

SDR submitted:

Shortly after departure, the left hand engine forward upper cowling latch (aft right hand side) opened in flight. The pilot then returned the aeroplane to the same airfield without incident.

Maintenance removed the cowling, inspected and found no defects in the latching mechanism. The aeroplane was then returned to service.

Transport Canada Comments: 

Further investigation revealed several previous events of a very similar nature. 

The cowl latch design is such that if not properly configured prior to installation; then it is possible that hook to pin engagement may not occur, even though the external safety markings would indicate that the cowls were latched.

It is recommended that prior to closing the cowls; ensure that the lock lever or trigger is visible and slightly protruding into the hook radius. A thorough verification of a successful latch is essential.


Wiring Harness Damage and Arcing

SDR # 20120323002

SDR submitted:

During the pilot walk around, the baggage light circuit breaker (C/B) was noted as “popped” or out. After a reset the C/B immediately popped. Maintenance removed the baggage panels in order to inspect a suspected wiring harness run and with the ceiling panels down, the maintenance technician noted a flash when the light switch was turned on.

Further inspection found two wires chafed through the insulation by the auxiliary power unit (APU) intake duct.

The wires were repaired and the clamp holding the bundle was adjusted for better clearance and the aeroplane was released for service.

Harness arcing damage

Transport Canada Comments: 

Proper harness support and protection to prevent occurrences as stated is essential for the safe continued operation of all aeroplanes.


Landing Gear Door Rod-end Failure

SDR # 20120605007

SDR submitted:

During gear retraction and extension, the pilot heard a loud bang. The aeroplane landed without incident and maintenance found the right-hand forward gear door rod-end broken.

The rod-end assembly was replaced and the aeroplane was made serviceable.

Gear door rod-end failure

Transport Canada Comments: 

Transport Canada Civil Aviation (TCCA) is advising all Mitsubishi MU-2B60 owners, operators and maintainers to pay close attention to the main landing gear door rod-ends for possible signs of cracks.


Loose Terminal Lugs

SDR # 20120306008

SDR submitted:

A defect was recorded where the battery assist function was inoperative (secondary start) which was rectified by the replacement of the left-hand power junction box (LHPJB). A few days later a defect was recorded: “generator 1 bus crew advisory status CAS message, unable to clear”. While conducting troubleshooting with the external power on, the battery 1 voltage drained down below 20 volts. During further troubleshooting it was confirmed that the battery 1 generally would not charge with external power connected and would continue to discharge, with the exception of a few instances when battery 1 would receive a partial charge (approximately 27 volts from a 28.5 external power unit). During engine runs, it was also confirmed that the secondary start sequence was not functioning. Additionally there was no load sharing when generator 1 or generator 2 was turned off line where it was suspected that the bus tie was not closing.

Extensive trouble shooting was carried out with no faults found. The left-hand power junction box was again replaced with nil fix. While removing the right-hand power junction box for replacement, the two rear connections at Terminal 2 and Terminal 3 were found to be significantly loose and arcing on the lugs.

The lugs were tightened and the system was tested serviceable. The right-hand junction box was replaced due to terminal lug damage.

Loose T2 and T3 terminal lugs

Transport Canada Comments: 

Another example of the difficulties that can be encountered when troubleshooting electrical snags on an aeroplane.

It is suspected that due to the finding where both terminal attachments were loose, previous maintenance work in this area was performed where the error was induced.


Aft Wing Spar Area – Severe Corrosion

SDR # 20120202006 & 20100226005

SDR submitted:

A visual inspection of the wing rear spar attachment fitting (using light and mirror) (Wing Rib Station 24) revealed evidence of corrosion. This area is very difficult to inspect (no inspection panel), thus a video camera was needed to facilitate a more detailed inspection.

Subsequently, a detailed inspection using the camera revealed cracks on the steel aft spar plate attachment fitting, part number (P/N) 66762-000, located on the aft wing spar. Severe, dissimilar metal related corrosion was also found between the rear wing spar and the spar plate attachment fitting.

An earlier Service Difficulty Report reported similar corrosion in this same area. It appears that the aluminum spar and steel attachment fitting were assembled during manufacturing process without corrosion preventive protection. Initially, some metal flaking was visible, but upon disassembly; it was found that over 50% of the aft left-hand spar fitting was degraded by corrosion.

A wing rear spar attachment fitting (Wing Rib Station 24) with evidence of corrosion.
: A corroded aft spar fitting (steel plate)

Transport Canada Comments:

Transport Canada Civil Aviation (TCCA) highly recommended that owner/operators comply with Piper Service Bulletin (SB) 977 (applicable to PA-28/PA-32, PA-34 &PA-44 series) and carry out a one-time inspection and other recommended corrective action. The installation of these access panels to the rear floorboards will then allow maintenance personnel to conduct a thorough corrosion related inspection of this important area. Additionally, TCCA recommend that operators also comply with the inspection procedures outlined in Piper SB 789A.

In the interim, it is recommended that maintenance personnel use a video camera or a small borescope to access this area to carry out these inspections.


Potable Water Level Sensor Failure Causing Smoke in Aeroplane

SDR # 20120319005

SDR submitted:

After 4 hours into flight, electrical burning smell from the crew rest area was noticed. The smell was confirmed by pilots and cabin smoke emergency procedure was initiated. After pulling galley circuit breakers and turning the recirculation fan off, the smell dissipated and then came back a second time.

An emergency was declared and the flight was diverted without further incident. After cabin smoke procedure was completed, electrical fire procedures were carried out and the burning smell abated to a certain degree until landing.

Investigation found that a water level sensor was the cause of the smoke. The unit was sent for testing with the following results:

The lab report suggests that a crack was likely caused by an over torque situation probably during installation of the unit. Water from the tank was able to penetrate the sensor body and cause the failure of the device.

Damaged sensor with evidence of rust on sensor body. Arrow pointing to an area of rust from under the polusufone plastic.

Transport Canada Comments: 

While a potable water system might not seem like an airworthiness item, maintainers are reminded that all system installed on or in an aeroplane are subject to the same rules and regulations. As much care and vigilance must be used when installing these systems as any other component.

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