Fixed Wing

Cargo Door Retract Actuator Frame Mount Failure 

Aerospatiale ATR 42-320
(SDR) # 20121109009

SDR submitted:

Maintenance reported that during a regular inspection, it was noticed that the cargo door wasn`t opening fully causing the actuator to run to its limit. During investigation, it was noticed that the cargo door seemed overly flexible and presented more sway than expected.

When the cargo door interior panel was opened, a crack was found emanating from the retract actuator frame mount attachment point.

The frame was repaired and the aeroplane was made serviceable.

Cargo door retract actuator supporting mount structure crack

Transport Canada Comments:  

Through discussions with Aerospatiale Continuing Airworthiness engineering, it was determined that this condition does not impose a detrimental effect to flight safety and the repair is covered by the Structural Repair Manual (SRM) 52-31-00.

Transport Canada Civil Aviation is advising all ATR 42 owners, operators and maintainers of this possible condition.

Fuel Crossfeed Bellcrank Lever Corrosion

BAE - (Raytheon), Hawker 800XP
(SDR) # 20121120006

SDR submitted:

During a routine heavy maintenance 48 month inspection for corrosion, maintenance found the fuel crossfeed bellcrank lever severely pitted and corroded beyond acceptable repair limits.

The bellcrank lever was replaced with a new part in accordance with the Aircraft Maintenance Manual (AMM) 28-20-00. 

Total part time since new was 3900 hours and time cycles since new 2475.

A corroded fuel crossfeed bellcrank lever

Transport Canada Comments:

An important item to be aware of when performing a corrosion inspection on Hawker 800XP aeroplanes. 

Aileron Hinge Bracket Corrosion

Piper PA-32R-301
(SDR) # 20121114001

SDR submitted:

During removal of the right hand aileron for painting, the Aircraft Maintenance Engineer discovered severe corrosion on the inside hinge that reduced the bracket thickness to about 60%-70% of the original manufactured thickness. Corrosion was also found on the left-hand aileron hinge bracket.

Consequently, all 4 hinge brackets were replaced on the right-hand and left-hand ailerons.

Aileron Hinge Bracket Corrosion

Transport Canada Comments:

Transport Canada Civil Aviation (TCCA) investigated further and found 1 previous Service Difficulty Report (SDR) that reported aileron hinge bracket corrosion. Additionally, the Federal Aviation Administration (FAA) have published the following Special Airworthiness Information Bulletins (SAIB) pertaining to corrosion related problems on Piper PA-28, PA-32, PA-34 and PA-44 aeroplane models.

TCCA recommend that owners/operators comply with the FAA corrosion related recommendations contained within these SAIB(s):

  • CE-11-10 (flap hinges/brackets/ribs),
  • CE-11-12 (wing rear spar fuselage attach fittings),
  • CE-11-13(wing front spar corrosion) and,
  • CE-11-14 (vertical forward stab attach point).

Rudder Pedal - Broken

Beech 200
(SDR) # 20120510005

SDR submitted:

During taxi operations, the pilot reported that the left-hand rudder pedal unit broke. The pedal was subsequently replaced with a new assembly. In addition, the left-hand rudder pedal arm shaft bracket taper pin was also found to be excessively worn and had to be replaced.

As a precautionary measure, the remaining rudder pedals were inspected and as a result the right-hand rudder arm to pedal attachment point was found to have excessive play and was worn beyond specified limits.

Transport Canada Comments:

The rudder pedal assembly is constantly undergoing various stresses that over a short period of time can result in excessive wear and stress cracks.

This is an area that requires regular attention as exemplified in the above scenario and this operator’s responsible follow-up action resulted in the following finding: the pilot and co-pilot rudder pedal arms, part number 50-524326-33, worn to limits at the upper bushings.

Rudder Trim Cables - Reversed

Beech 95
(SDR) # 20120809014

SDR submitted:

During cruise flight, the pilot attempted to centre the ball in the “Turn and Bank Indicator” by applying rudder trim, however the effect was opposite to normal (turned trim wheel left but the right rudder trim was noted to move). Soon afterwards, the pilot landed and maintenance personnel later confirmed that the rudder trim system was operating in reverse.

A complete inspection revealed that the rudder trim cables exiting the rear bulkhead to nearby pulleys that direct trim cables up the vertical stabilizer were confirmed to be routed incorrectly. Maintenance rigged the trim cables correctly followed by a dual inspection check by qualified personnel. Company quality assurance investigation revealed that this aircraft was imported some 6 years ago and verified that the rudder system had not altered during the importation process nor since that time.

During these last 6 years, both flight crews and maintenance personnel had missed this potentially dangerous flight control error. Proper rudder control input would be critical during an engine failure in order to assist flying with asymmetrical thrust, especially in the fire suppression role/low altitude role that this particular aircraft is engaged in.

Flight training (“engine out” procedures) is conducted on a similar Baron with dual flight controls which may be one of the reasons that this rudder trim rigging error was not detected on the occurrence aircraft. Another reason could be that the cockpit rudder trim indicator is labeled “Rudder Tab” and the control wheel mechanism is labeled “Left-Rudder Tab-Right”. Most rudder trims are identified as “Nose Left or Nose Right”.


Rudder trim cables crossed at the rear bulkhead

Transport Canada Comments:

These types of flight control errors would not have occurred if personnel following the maintenance instructions subsequently conducted dual independent inspections. 

Alarmingly, these types of occurrences continue to occur on both the rudder and elevator trim systems and have resulted in fatal occurrences. It is strongly recommended that dual inspections be carried out as well as conducting visual checks on the actual flight tab position to ensure it corresponds correctly with the cockpit indicated positions.

Slat Actuator Supporting Mount Failure

Boeing 727-243
(SDR) # 20121122007

SDR submitted:

Upon selecting flaps down on approach, the crew noticed a hydraulic system low pressure light and corresponding loss of quantity. The crew declared an emergency and landed without incident. Maintenance discovered the #2 slat actuator had broken from its upper mount and moved aft, shearing a hydraulic line which caused the loss of the hydraulic system and damaging an anti-ice pneumatic duct.

The flap actuator supporting mount was repaired, the hydraulic line and pneumatic duct replaced and the hydraulic system re-serviced, making the aeroplane serviceable.

Failed flap actuator supporting bracket causing a complete hydraulic system failure and damaging an anti-ice pneumatic duct

Transport Canada Comments:  

Upon review of the Web Service Difficulty Reporting System (WSDRS) database, additional occurrences were noted where Boeing Service Bulletin (SB) 727-57-0130 has been released to strengthen the slat actuator mount bracket.

Insufficient Hydraulic Line Support

Bombardier CL-600-2D15
(SDR) # 20121109008

SDR submitted:

While applying take-off power at the start of the take-off roll, the #1 engine driven pump (EDP) caution message came on and the #1 hydraulic quantity went to zero.

Maintenance investigation found a chaffed hydraulic line in the aft equipment bay that caused the loss of the hydraulic fluid. The line had chaffed against stringer #7 due to a broken retaining “L” bracket.

The hydraulic line and “L” bracket were replaced and the damage to the stringer was repaired making the aeroplane serviceable.

Hydraulic retaining “L” bracket broken and hydraulic line chaffing condition

Transport Canada Comments:  

When performing service checks and walkarounds, it’s important to inspect for the serviceable condition of hydraulic line retaining brackets and clamps.

Bent Nose Landing Gear Centering Bracket

Canadair CL-600-2B16
(SDR) # 20131230006

SDR submitted:

Upon selecting the landing gear up after departure, only the main landing gear retracted. The nose landing gear (NLG) stayed down and locked and the crew returned for an uneventful landing.

Maintenance personnel traced the fault to the NLG centering sensor bracket which is believed to have been bent during a previous towbarless ground handling movement. It is suspected that the towbarless tugs strut strap had been mistakenly placed around the NLG strut centering bracket.

The NLG centering sensor bracket was replaced and the aeroplane was returned to service.

Damaged nose landing gear centering sensor bracket

Transport Canada Comments:  

The use of towbarless tugs are now a common sight at airports around the world and this style of ground support equipment (GSE) provides better aeroplane controllability and maneuverability as compared to a standard towbar & tug configuration.

As stated by the operator, Bombardier Advisory Wire 600T-2171 has been issued identifying the possible scenario where damage to the NLG when using a towbarless tug can occur.

Transport Canada Civil Aviation is advising all owners, operators and maintainers of this possible scenario and available Bombardier documentation.

Burnt - #2 Engine Intake Adaptor Heater

(SDR) # 20110802002

SDR submitted:

During descent through 6000 feet altitude, the #2 engine inlet adaptor heat caution light warning illuminated. Each time, the inlet bypass door was pressed, the circuit breaker for the #2 lip heater would “pop”. The crew continued the descent to exit the icing conditions, then proceeded to fly a normal circuit and landed with the engine intake de-icing system turned off.

An investigation by line maintenance personnel revealed that the engine intake adaptor heater was severely damaged from a significant overheat event during operation. Soot evidence in the engine area indicates possible flames were generated; however the crew received no cockpit fire indication advisories. Evidence of soot damage was also found in the area of the electrical connector area for the heater.

The failed intake adaptor heater was quarantined and has been sent to the manufacturer for further analysis.

Exterior damage to #2 engine intake

Transport Canada Comments:  

A review of the Service Difficulty Report (SDR) database has revealed previous failure events where the crew smelt a burning odor entering the aeroplane. In particular, one significant ground event (2004) reported smoke and flames coming from the engine cowling and air intake section caused by a failed intake adaptor heater (pre-mod part number (P/N) 4100S028-01).

Investigation by the manufacturer (Zodiac Aerospace) of the engine inlet adaptor heater revealed that during manufacturing process, the heating element is difficult to place with the casting and as a result it can cause overheating during the manufacturing process or in the field. In the interim, it is recommended that maintainers routinely inspect for any visible damage to the engine inlet area and associated electrical connectors.

Engine Oil Cooler Bypass Valves – Failures

DHC-8-400 series
(SDR) # 20120910001

SDR submitted:

A number of DHC-8-400 operators have reported engine shutdowns due to high oil temperature caused by the failures of oil cooler bypass valves part number (P/N) D2887 355C. This has resulted in numerous air turnbacks and a decreased level of safety.

Bombardier have taken corrective action and have introduced a new configuration of valve (P/N D2887-955C) that incorporates an advanced polymer sleeve that will resist the swelling of the current internal rubber sleeve that was the root cause of this valve’s failures. Installation of the new valve P/N D2887-955C will also change the oil cooler assembly from a D2887-815A to D2887-915A

Bombardier also recommends that operators apply a soft time to the air cooler thermal valve P/N D2887-355C at 3000 hours to avoid in-flight shutdowns or high oil pressure indication.

Transport Canada Comments:  

Transport Canada Civil Aviation recommends that all operators install the new configuration P/N D2887-955C valve at the first opportunity. In the interim, please comply with the soft time of 3000 hours when using the older style P/N D2887-355C oil cooler valve. More specific information is contained within Bombardier document DH8-400-SL-71-014.

Bombardier has now introduced SB 84-79-06 “Improved Engine Oil Cooler Bypass Valve”.

Chafed Radiator Pipe

Diamond DA20-A1
(SDR) # 20110107005

SDR submitted:

During a routine inspection, it was found that the springs that hold the exhaust muffler in place were rubbing against the radiator pipe. Because this is a confined area, the pipe was removed for further inspection. It was then discovered that the radiator pipe was almost entirely chafed through.

A loss of engine coolant during flight would have resulted in an in-flight shutdown with possible heat related damage to the engine. This is the 3rd time chaffing was reported in this area.

Diamond has informed operators that when the flexible coolant hoses are replaced, that the aluminum radiator pipe needs to be the correct distance away from the exhaust springs.

Transport Canada Comments:  

As with all adjacent components and parts, always ensure that adequate clearances exist. This is especially true in tightly confined, hard to access areas.

Melted Pitot Static Lines

Douglas DC3C
(SDR) # 20130129007

SDR submitted:

The flight crew reported to maintenance that the captain’s airspeed indicator was reading up to 40 knots lower than the co-pilot’s airspeed in flight. Maintenance performed a pitot static leak check and visual inspection of the aeroplane revealing that both the captain’s pitot and static plastic lines were melted from contacting a cockpit under-floor heater duct.

The pitot and static plastic lines were routed adjacent to a heater duct, causing the contact and eventual melting of the pitot-static lines.

The affected pitot-static lines were replaced and precaution was taken to relocate the replacement lines at a suitable distance away from the heater ducts, making the aeroplane serviceable.

Melted pitot-static lines due to contact with a heater duct

Transport Canada Comments:  

As stated by the operator, the work done to relocate the plastic lines was in accordance with Federal Aviation Administration (FAA) Advisory Circular (AC) 43.13-1B and 2B since the existing original equipment manufacturer (OEM) maintenance manual did not provide sufficient instructions to correct the problem.

Aileron In-Flight Jam Condition

Fairchild SA227-DC
(SDR) # 20120821006

SDR submitted:

The aileron system of the aeroplane temporarily jammed in flight. The system was troubleshot and the jam appeared to be coming from the copilot control wheel. At first it was thought to be faulty bearings at the control wheel so they were replaced and re shimmed as per the Aircraft Maintenance Manual (AMM).

Further investigation found that the chain was binding at the control wheel sprocket area within the control column. The chain looked dry (no lube), its link rollers worn and showed evidence of wear at the link joints. There was also evidence of the chain contacting the insides of the control columns housing (slight loss of metal and primer).

The chain was replaced and lubed, making the aeroplane serviceable.

Aileron control wheel cable chain link roller with wear marks

Transport Canada Comments:  

As commented by the operator and through extensive investigations from the original equipment manufacturer (OEM), M7, it’s now understood that the aileron control wheel jam was caused by a combination of a lack of lubrication and excessive wear on the chain link rollers. With the excessive wear of the chain and a control wheel roll input applied, the chain would have a tendency to ride up the control wheel sprocket teeth and bind through contact with the inside wall of the control column housing.

Also noted by the operator was an error in the AMM which omitted to include the specific lubrication of the aileron control wheel chain.

M7 has produced Service Bulletins 27-001R2, 27-026R2, 27-054R2 and 27-074 to address this issue including corrections to the affected AMM.

Corrosion In Float Aeroplane Avionics

Honeywell, Equipment
(SDR) # 20121115008

SDR submitted:

The subject aeroplane was brought to an avionics repair shop with an autopilot snag. It was determined that the pitch servo had sustained water damage that resulted in corrosion and an intermittent short on the clutch engage wire. This in turn caused the failure of a transistor. To rectify the problem, the autopilot computer was repaired and the pitch servo was replaced. The aeroplane is equipped with amphibious floats and has drainage holes in the bottom fuselage.

Autopilot Servo With Corroded Transistor

Transport Canada Comments:  

Corrosion in float aeroplanes is an ongoing concern. Avionics components are also subject to corrosion internally and must be considered when conducting inspections.

Nose Landing Gear - Improper Servicing

Learjet 60
(SDR) # 20120821008

SDR submitted:

During landing at touchdown, the aeroplane veered hard left when approaching 105 knots where full right rudder and brake was applied to counteract the uncommanded turn. Once the left engine was brought out of reverse thrust, the aeroplane responded and abruptly swung back to center line where the aeroplane taxied normally from the runway.

Maintenance inspection found the nose landing gear (NLG) oleo was flat which prevented the internal NLG strut centering cam mechanism from aligning the NLG wheel prior to touch-down.

The NLG showed no indication of hydraulic fluid leakage where it was confirmed that the nitrogen gas charge was underserviced, causing the NLG wheel misalignment.

Nose Landing Gear Strut Static Deflection - Nose Gear Strut - Servicing

Transport Canada Comments:  

As stated by the operator, a correctly serviced NLG oleo requires only 75 PSI of nitrogen gas pressure and due to this low preset pressure, the oleo weight-on-wheels (WOW) extension is largely dependent on fuel load and aeroplane balance. This may be misleading to maintenance personnel and the flight crew when performing the pre-flight walk-around check in understanding if the NLG has proper oleo extension.

The Aircraft Maintenance Manual (AMM) defines two types of procedures or methods to service the NLG strut for correct oleo extension. The “Preferred Method” requires the provisions to jack the aeroplane in order to accomplish the correct landing gear servicing while the “Alternate Method” enables the maintenance provider to service the gear while the aeroplane is on ground or WOW, but requires the aeroplane to be full of fuel.

The attached figure represents the required oleo extension when referencing the “Alternate method” AMM servicing procedure.

Recently, Learjet issued Service Bulletin SB 60-11-4 which provides the installation of a service instructions name plate on the NLG strut that defines the AMM “Preferred Method” servicing procedures.

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