Fixed Wing

BEECH 200
SDR # 20100930007
 
Electrical Dual Bus Diode – Failed

SDR submitted:

On approach and following the landing gear “down” selection; there was an immediate loss of all engine instruments other than the R/H engine torque gauge. In addition, the captain’s ADI, propeller auto feather, pitot heat and intercom function were lost. The crew also noted that there was no “gear down and locked” indication. The gear doors were open however, the gear was still in the wheel wells but slightly extended. All other aircraft indications were normal, no circuit breakers had popped and the inverters and generators appeared to be functioning normally.

The crew then declared an emergency and diverted to the nearest airport with emergency facilities. On approach to the alternate airport; the crew manually extended the landing gear; however, there was still no “green” indications. Just before final landing; all of the failed aircraft systems indications came back on line, including all three of the landing gear “green” indications. An uneventful landing was carried out.

Maintenance was dispatched to investigate and found the wire number P11A6 between terminal block 106 and dual bus diode assembly was loose. It was found that additional heat had damaged the CR2 diode. The CR2 diode was replaced on #2 bus diode assemblies and the wire was re-torqued. Dual bus conformity check was then completed in accordance with the aircraft maintenance instructions.

The aircraft returned to home base and inspected further as a precautionary measure related to the R/H bus failure. Wire P11A6 between terminal block 106 and the dual bus diode was replaced due to possible heat damage. The operator stated that a defect history search revealed no other similar events of this specific nature.

Transport Canada Comments:
When inspecting or installing power diodes; it is important to ensure that the diode is firmly attached to its respective mounting, which serves as a heat sink. Diodes that carry substantial current will become overheated/damaged unless the heat is conducted away by the mounting structure. It is important to have maximum metal-to-metal contact between the base of the diode and the mounting structure. Electrical current and voltage ratings determine its physical size of a diode with the larger power diodes capable of carrying over 2500A. Hammer and wrench in X formation indicating end of article

BOEING 767 375
SDR # 20101105002
 
Fuel Imbalance Fault Findings

SDR submitted:

The aeroplane had repeat logbook snag entries for left wing fuel imbalances. After multiple No-Fault-Found (NFF), maintenance troubleshooting eventually led to the finding of a fuel pressure line coming from the left centre tank override pump being chaffed through.

The fuel line was replaced and the aeroplane made serviceable.

Transport Canada Comments:
Fuel imbalances on any aeroplane size and type can cause serious operational concerns if the flight crew is not able to properly address the fault while in flight.

It is essential that a complete and thorough internal and external fuel system component inspection be done when a fuel imbalance snag is raised. Hammer and wrench in X formation indicating end of article

Fuel Imbalance Fault Findings

DHC 8 301
SDR # 20101126002
 
Hydraulic Mist in Cockpit (Ruptured Hose)

SDR submitted:

After take-off and during landing gear up selection; a loud “whooshing” sound was heard by the crew and what appeared at the time to be smoke coming from behind the instrument panel. Shortly thereafter, it was soon realized that it was mist and fumes from hydraulic fluid. The crew was able to don their respective facemasks but not before undergoing extreme respiratory distress and eye irritation.

Subsequent maintenance investigation found that the nose landing gear “up line” had ruptured below the flight compartment floor between FS 37 and FS 97. The fumes had migrated into the cockpit area.

Transport Canada Comments:
Transport Canada Civil Aviation recommends that operators comply with Bombardier Aerospace Service Bulletins 8-29-32 (Cryoflare Hydraulic Fittings) and 8-29-41 (CRES Hydraulic Tubing). Hammer and wrench in X formation indicating end of article

BOEING, 777 333ER
SDR # 20101019013
 
Engine Harness Chaffing and Arcing

SDR submitted:

During maintenance troubleshooting for multiple auto-throttle disconnect snags, a harness on the #2 engine fan casing was found chaffed with evidence of arcing at the 12 o’clock position. The affected wires were temporarily repaired and the aeroplane was made serviceable.

Transport Canada Comments:
Any form of wire chaffing has the potential for arcing and it is essential that it be quickly corrected. Measures should also be taken to prevent possible future events.

Presently, Transport Canada Civil Aviation is working with the manufacturer, General Electric, to investigate for possible additional harness supports. Hammer and wrench in X formation indicating end of article

Engine Harness Chaffing and Arcing

BOMBARDIER, CL600 2C10 (RJ700)
SDR # 20101026007
 
Elevator PCU Rod End Breakage

SDR submitted:

While performing a maintenance task card for an operational check of all elevator PCU’s, hydraulic system #1 PCU for the L/H elevator would not return to the neutral position after being pushed to the full nose up position. Maintenance removed the access panel to inspect the elevator PCU area and it was noted that the PCU Rod End had broken free from the PCU Piston. It was later confirmed that the Rod End Bearing and the bolt were both seized, stressing this attachment point and causing the breakage.

A new PCU was installed, the maintenance task card passed all tests and the aeroplane was made serviceable.

Transport Canada Comments:
Lubrication of all attaching fasteners and hardware is essential for correct and enduring mechanical operations.

Transport Canada Civil Aviation is presently working with Bombardier in determining if all of the Instructions for Continuing Airworthiness (ICA’s) is suitable to prevent occurrences as seen below. Hammer and wrench in X formation indicating end of article

Elevator PCU Rod End Breakage

BOMBARDIER, CL600 2D24 (RJ900)
SDR # 20100813018
 
Brake Disk Failure

SDR submitted:

During a routine replacement of the L/H out-board wheel assembly, the technician encountered difficulties installing the tire back on to the main landing gear axle. After a closer inspection, it was noted that one of the five brake carrier assembly rotor disks had fractured, allowing the disk to protrude and prevent the wheel from being fully installed.

The brake assembly was replaced, the new wheel assembly installed and the aeroplane was made serviceable.

Transport Canada Comments:
During any form of routine maintenance, even a tire change as stated above, it is essential that all adjoining critical systems be visually inspected prior to the installation of the replacement part as stated in the Aircraft Maintenance Manual. Hammer and wrench in X formation indicating end of article

Brake Disk Failure | Fractured and protruding brake disk rotor

CESSNA 441
SDR # 20101012002
 
Burnt Electrical Wires – Aft Spar Area

SDR submitted:

Following a return flight, the crew reported that the R/H auxiliary fuel tank pump was not working. The landing light was inoperative and the circuit breaker kept “popping” when reset.

It was found during troubleshooting that 7 heavy gauge electrical wires that run along the aft side of the aft spar (intersection of fuselage station (FS) 212.00 and wing station (WS) 40.00) had completely burnt through. The R/H fire bottle was found empty and it is believed that the electrical shorting within the wire bundle was the cause. Electrical wires were found loosely hanging down, inadequately clamped and had been chafing on a rivet head.

Transport Canada Comments:
It is essential that personnel pay extra attention to visually inspect electrical wiring, especially on older aircraft. Hammer and wrench in X formation indicating end of article

Burnt Electrical Wires – Aft Spar Area

DHC 8 400
SDR # 20101203002
 
R/H MLG Unsafe Indication – Jammed Grease Nipple

SDR submitted:

An operator reported an incident in which the aircraft landed with a R/H MLG indication “red unsafe light illuminated”, and no illumination of the R/H “green down and locked light”; both on the cockpit landing gear selector panel and the Alternate Landing Gear indication panel. The unsafe indication illuminated following a normal gear selection.

The crew then used the Alternate Landing Gear extension procedure; however, the R/H MLG still indicated an unsafe position. The flight crew then shutdown the R/H engine and performed an uneventful single engine landing.

A post-occurrence inspection revealed that a grease nipple had somehow dislodged from the R/H landing gear and became jammed in the R/H MLG lock actuator. This prevented the R/H MLG lock mechanism from fully locking down as well as providing an unsafe (green down and locked) both in the normal and alternate positions. It is believed that the grease nipple had dislodged from the aft lock link, which is located on the aft MLG stabilizer brace assembly.

A closer inspection of this area found that numerous other grease nipples were missing at various locations.

Transport Canada Comments:
Further to the above, we highly recommend that operators and maintenance facilities adhere to the recent All Operators Message No. 431 issued by Bombardier Aerospace.

This type of grease nipple is common to a number of other aircraft types.

It is thus recommended that all maintenance personnel routinely check for loose or missing grease nipples. Hammer and wrench in X formation indicating end of article

R/H MLG Unsafe Indication – Jammed Grease Nipple

FAIRCHILD, SA227AC
SDR # 20100811010
 
Bleed Duct Induced Crack

SDR submitted:

During some troubleshooting maintenance work for a hydraulic leak, the L/H cooling turbine, bleed air tube and associated plumbing were removed to gain access to a failed hydraulic component. Upon inspection of the bleed air tube, prior to reinstallation, it was noted that there was a circumferential crack along the flange weld. The crack had progressed significantly around the tube, almost to the point of complete failure. It was also noticed that at the widest point in the crack, there was what appeared to be a screwdriver tool mark, more than likely induced at an earlier removal of the tube when attempting to remove the V-clamp.

The bleed air tube was replaced, leak checks and functionals carried out and the aeroplane was made serviceable.

Transport Canada Comments:
The tools that are used to fix and repair the aeroplanes we maintain can also inflict damage if not used correctly as seen below.

With this case in removing a seized V-clamp, a rubber mallet or composite punch would have been the appropriate tool. Hammer and wrench in X formation indicating end of article

Bleed Duct Induced Crack | Inflicted screwdriver tooling mark

FAIRCHILD, SA227AC
SDR # 20101019010
 
Missing Washer At The Rudder Pedal Torque Tube

SDR submitted:

A “clunk” was heard when the brakes were applied on the captains side rudder pedal area during taxi. Upon inspection by maintenance, the rudder pedal torque-tube attaching fasteners nut was pulled through the bushing hole.

The nut was removed and the required washer installed as per the original equipment manufacturer (OEM) IPC and AMM 27-20-30 manuals, and the aeroplane was made serviceable.

As a proactive and precautionary follow-up, all aeroplanes in the operators fleet were checked to ensure there were no missing washers at the rudder pedal torque-tube area.

Transport Canada Comments:
Fastener hardware with the use of washers for correct nut support is essential for the continued airworthiness of all aeroplanes and is considered a standard practice for most installations.

The referencing of all required OEM manuals during the disassembly and reassembly of aeroplane equipment must be followed at all times. Hammer and wrench in X formation indicating end of article

Missing Washer At The Rudder Pedal Torque Tube | Nut pulled through due to no washer

FAIRCHILD, SA227CC
SDR # 20101022002
 
Main Landing Gear Torque-Link Failure

SDR submitted:

During taxi, the L/H main landing gear (MLG) lower strut torque knee attachment boss fractured and separated from the lower gear strut assembly causing a severe shimmy.

The MLG strut assembly was replaced and the aeroplane was made serviceable.

Transport Canada Comments:
Upon further evaluation, it was discovered that a past-unapproved repair was accomplished on the gear, which in turn weakened the lower scissor attachment lug, leading to its failure.

It is important to note that SRM 54-90-50 in reference to the repair of worn MLG upper/lower torque link lugs is to be followed and any other repair deviation must be supported with official OEM approval documents. Hammer and wrench in X formation indicating end of article

Main Landing Gear Torque-Link Failure

PIPER PA31
SDR # 20100813002
 
Engine Exhaust Fire – Burnt Cowling

SDR submitted:

During flight, the crew noticed smoke coming from the R/H engine area. Following an uneventful landing, maintenance personnel found that the upper and lower tailpipes were seized together. The intense heat and fire caused a complete burn-thru on the R/H cowling just aft of the exhaust louvre.

Transport Canada Comments:
A review of the SDR database revealed numerous defect reports on tailpipes due to cracks at the weld areas, flanges and also at the “waste gate” areas.

The importance of regular inspections and maintenance of exhaust systems cannot be overemphasized. Exhaust system components are subjected to extreme temperatures and resulting expansion and contraction produce stresses, which often lead to cracks and distortion due to warpage. Hammer and wrench in X formation indicating end of article

Engine Exhaust Fire – Burnt Cowling

PIPER PA44 180
SDR # 20100512006
 
Nose Landing Gear Drag Link Assembly

SDR submitted:

After a hard landing; the pilot noticed that the nose gear was not indicating in the normal down position.

Maintenance later found damage at the nose gear upper drag link; where it attaches to the lower link assembly. The proper drag link pivot bolt was found undamaged, however the upper drag link showed signs of an existing crack located in an area that is difficult to inspect when the gear is down and locked.

Transport Canada Comments:
Service history investigation has revealed previous cracks of the drag link assembly, trunnion and also numerous failures of the nose gear pivot bolt. Failures of this nature have resulted in collapse of the nose gear assembly. The drag link is designed to stabilize the landing gear assembly longitudinally and thus performs a major function during landing and taxi operations.

Be particularly attentive to the above problems when inspecting the nose gear areas, particularly after a hard landing. Hammer and wrench in X formation indicating end of article

Nose Landing Gear Drag Link Assembly | Upper Drag Brace Assembly | Lower Drag Brace Assembly | Upper Drag Brace attaches to lower drag brace onto this NAS bolt.

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