Fixed Wing

Seized Ram Air Turbine Uplock Roller

AIRBUS, A310-304
SDR # 20110513007

SDR submitted:

Maintenance was performing an operational task of the ram air turbine (RAT) uplock mechanism during an A-06 check when it was discovered that the RAT failed to deploy from both the captains and first officers release handle.

After the investigation it was found that the uplock roller on the RAT was seized. 

The RAT uplock roller was disassembled, inspected, re-lubricated, reassembled and made serviceable through a successful operational test.

Transport Canada Comments:

Further evaluation from the operator for the remaining A310 aeroplanes revealed similar problems where the operator decided to de-escalate the operational task of the RAT and introduce a lubrication repeat task into their maintenance program.

Failed Anti-ice Duct

BOEING, 767-375
SDR # 20120312014

SDR submitted:

After arriving at the gate and during a standard walk-around, maintenance discovered at the left wing, the #4 slat inboard blow out panel blown out with no anti-icing duct visible from the opening.

Further inspection revealed the ducts to be disintegrated and frayed with strands of tube material blocking the inside of the anti-icing ducts. Another anti-ice duct was also found damaged on the same wing outboard of the engine.

Both ducts were replaced making the aeroplane serviceable.

Transport Canada Comments:

Through the close scrutiny of the maintenance personnel while performing the walk-around, the observation of the dislodged blow-out panel revealed the failure of the ducts prior to departure.

A job well done for the maintenance engineer involved.

Nose Landing Gear Upper Drag-Brace Fracture

SDR # 20120410003

SDR submitted:

During removal of the nose landing gear assembly, the upper drag-brace trunnion casting was found cracked approximately 75% of its circumference.

The drag brace trunnion was replaced, making the aeroplane serviceable.

Transport Canada Comments:

Yet another example of the importance of the daily checks that should detect faults as seen here before the flight of the aeroplane.

Windshield Failure

SDR # 20111109001

SDR submitted:

On descent into destination, the captain’s windshield shattered. The flight continued to destination and landed safely. The aeroplane was removed from service for maintenance to replace the left-hand windshield.

All operational tests were carried out making the aeroplane serviceable.

Transport Canada Comments:

It was noted by the operator that there was erosion of the outboard upper rubber seal or “moisture seal” which may have allowed moisture to permeate and cause the outer pane of this windshield to fail.

As stated in the applicable Aircraft Maintenance Manual (AMM) 56-11-01, “inspect the outboard moisture seal for cracks or erosion… and repair if necessary…”

Transport Canada Civil Aviation is advising all owners, operators and maintainers of the aforementioned AMM reference for various inspections and repairs that are available to prevent such occurrences as seen in this article.

Fractured Aileron Output Link

SDR # 20120528007

SDR submitted:

During a scheduled heavy maintenance inspection for a functional check of the two aileron power control units (PCU) at each aileron panel, the aircraft maintenance engineer (AME) found one of the two PCU output links on the right-hand aileron panel fractured and separated.

The output link was replaced and the system was brought back to a serviceable condition.

Transport Canada Comments:

The maintenance program of this aeroplane has been developed to capture failures such as this in order to prevent a complete failure of the flight control system.

Transport Canada Civil Aviation is advising all owners, operators and maintainers of this potential dormant failure and to be sensitive to flight crew snags related to this system.

Wiring Overheat Damage

SDR # 20120518001

SDR submitted:

While investigating an unrelated defect on the aeroplane, the Aircraft Maintenance Engineer discovered burnt wiring related to the 3A hydraulic pump power relay K1DB circuit. Wire # DB18B12WHT was burnt approximately 20.32 cm (8 inches) leading up to the power relay.

The affected wires were replaced as defined in the Electrical Standard Practices Manual and the aeroplane was returned to service.

Transport Canada Comments:

It is suspected that improper wire terminal crimping caused the wire overheat condition.

Transport Canada Civil Aviation (TCCA) is advising all aeroplane maintainers of the importance to diligently follow all manufacturer manual instructions when replacing aeroplane parts or performing repairs.

Cracked Drag-Angle

SDR # 20120501001

SDR submitted:

During a visit to a painting facility, cracks were found on the left-hand vertical stabilizer to fuselage attachment drag angles in both forward and aft positions.

The aeroplane was repaired in accordance with a Bombardier repair engineering order (REO) REO 690-55-31-010 and was later made serviceable.

Transport Canada Comments:

Transport Canada Civil Aviation (TCCA) is presently working with Bombardier engineering to better define this drag-angle failure characteristic and its implications.

TCCA is advising all CRJ700/900 owners and operators of this possible condition.

Horizontal Stabilizer Spar - Cracks

Cessna 172 series
SDR # 20120607001

SDR submitted:

An operator recently found a crack that went through the front spar and centre skin lightening hole area where the horizontal spar attaches to the fuselage (P/N 0532001-98).

This aeroplane previously had a crack in this same area despite the fact that the Cessna Horizontal Forward Spar Reinforcement Kit modification had been installed in accordance with Cessna SEB94-8.

Transport Canada Comments:

A service history review has revealed that these cracks are a longstanding problem that appears to be closely associated with improper ground handling.

Transport Canada Civil Aviation (TCCA) recommends that aviation personnel refrain from grabbing onto tail surfaces when manually moving these aeroplanes.

Main Gear Door Linkage

DHC-8-100 series
SDR # 20120418003

SDR submitted:

The crew reported loss of #2 hydraulic system pressure with rudder caution light and left hand (L/H) main landing gear unsafe light indications. The crew then cycled the landing gear to confirm that a problem existed and then returned to a nearby airfield for an uneventful landing.

Maintenance crew found that the outboard L/H main gear door pushrod (P/N 83231014-003) and corresponding spring assembly (P/N 83231020-003) failed. It appears that when the landing gear was deployed, an adjacent hydraulic line was severed resulting in rapid loss of fluid and loss of #2 hydraulic system.

Transport Canada Comments:

It is recommended that maintenance personnel closely inspect the landing gear doors and linkages to prevent future occurrences of this nature.

Cracked Rudder Pedals

SDR # 20120511001

SDR submitted:

During a 1500 hour inspection, the brake pedal, part number 22-2728-00-00, installed on the co-pilot’s side of the right brake and the brake pedal, part number 22-2727-13-00, installed on the pilot side of the left brake were both found cracked at the pivot tube. The pedals were not seized and no abnormal wear was found. Both pedals were replaced and the aeroplane was returned to service.

Transport Canada Comments:

Diamond Aircraft has increased the inspection/lubrication schedule on this item from 200 to 100 hour intervals. Details are given in current maintenance instructions and also in service information letter SIL20C1-003. This SIL is available to be viewed on Diamond Aircraft’s web site at:

Follow the link titled ‘Technical Publications’ and select service information letters.

Bad Installation of a Flap Torque-Tube Bracket

EMBRAER, ERJ 190-100
SDR # 20120611003

SDR submitted:

During a maintenance visit, the left-hand #6 flap drive torque tube was found worn and chaffed from the contact with a guide bracket. After power was re-established, the flaps were retracted and the torque tube was confirmed to be chaffing on the bracket. During a previous maintenance visit, the bracket had been installed in a way which allowed the torque tube to contact it during flap retraction causing the chaffing and wear.

The operational/rigging independent check accomplished at that time did not catch the tube contacting the bracket.

It was also confirmed that the torque tube contact on the bracket would not be apparent unless the flap system was operated to its fully deployed/extended and retracted/stowed position.

The torque tube and guide bracket were replaced while ensuring the correct orientation and installation of the bracket.

Transport Canada Comments:

As commented by the operator, the Aircraft Maintenance Manual (AMM) installation instructions are not clear in ensuring that this guide bracket is correctly orientated for its proper installation.

The Aircraft manufacturer, Embraer, was advised of this concern towards the unclear instructions in the AMM.

Transport Canada Civil Aviation is advising all maintainers of this possible scenario of the improper installation for this guide bracket.

Cabin Inverter Unit Failure

SDR # 20120425004

SDR submitted:

The right-hand non essential bus switch light illuminated as the crew lined up for take-off. They returned to the flight support ramp area and shut down the aeroplane. A very strong electrical burning odor was noted as maintenance disconnected the batteries in the aft equipment bay.

Maintenance conducted a complete inspection and noted that the root cause of the burning order was an unserviceable inverter.

Maintenance proceeded to replace the failed inverter, the upper main battery, the remote control circuit breaker and the right-hand non essential bus 80 amp fuse.

The complete system function tested good with no burning smell or overheat conditions and the aeroplane was returned to service.

Transport Canada Comments:

It has been found that condensation in the tailcone aft equipment bay may drip onto the inverter causing it to fail. Learjet Service Bulletin SB 45-25-24 will reduce this possibility of moisture entering the inverter and will direct the warm airflow from the inverter cooling fan away from the wiring that is routed above the inverter.

Transport Canada Civil Aviation is advising all Learjet 45 owners, operators and maintainers of the availability and importance to incorporate this Service Bulletin.

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