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Fixed Wing

Nose Landing Gear – Malfunction

Aero Commander 690
SERVICE DIFFICULTY REPORT
(SDR) # 20100702011

SDR submitted:

On take-off roll at rotation speed, the pilot noticed a violent nose wheel shimmy. The crew retracted the landing gear and continued to climb.

Once the aeroplane had leveled off; the pilot lowered the landing gear to investigate the gears functionality. However, the nose gear would not extend nor would the nose gear indicate a “down and locked” position. The landing gear was cycled several times but the nose gear would not fully extend despite all attempts to do so. The aeroplane returned to base and conducted two fly pasts that verified that the nose gear was down, but still the nose gear did not indicate a “locked” position. Upon touchdown, the engines were feathered and the pilot held the nose gear off the runway for as long as possible to minimize any damage.

The maintenance investigation revealed that a bolt that connects to the nose wheel steering actuator to the nose gear was missing. The actuator end spacer shaft (IPC Page 2-81, Fig 2-19, Item 75) was missing. The shaft is held into the spacer with a roll pin which was found sheared and had fallen out thereby leaving the nose wheel free and uncontrolled.

A Nose Landing Gear Installation with emphasis on the end spacer is depicted

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Illustrated Parts Catalog
Section II Landing Gear
ES10119
Nose Landing Gear Installation
 

Transport Canada Comments:
It appears that an incorrect installation was the root cause factor in this event, which endangered the crew and occupants of this aeroplane.

The operator has taken the appropriate internal action to ensure that maintenance personnel strictly adhere to the manufacturers aircraft manuals.

Nose Cowl Piccolo Tube Damage

BAE - UK, 3112
SDR # 20110921003

SDR submitted:

During a heavy maintenance visit, the right hand engine intake cowl was removed, where upon further inspection of the cowl; loose rivets were noticed behind the intake lip. The technician proceeded to remove the intake lip to further assess the pulled rivets. It was discovered that the attachment brackets had cracked and chaffed through the piccolo tube.

The piccolo tube and attaching brackets were replaced and the aeroplane was made serviceable.

A failed piccolo tube attachment bracket and incurred piccolo tube damage

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Failed piccolo tube attachment bracket and incurred piccolo tube damage

Transport Canada Comments:
Through research with the operator and BAE engineering, the cracking of the intake piccolo tube support brackets is a known issue and resulted in the release of an optional service bulletin 71-JA 930240 in 1993, which replaced the welded supports with new, flexible mounts.

Transport Canada Civil Aviation would like to advise all owners, operators and maintainers of the availability of this service bulletin and the importance of its embodiment.

Propeller Canon Plugs – Reverse Connection

BEECH 1900C
SDR # 20110505001

SDR submitted:

Shortly after departure, the aeroplane experienced an uncontrolled propeller pitch change from coarse to feather. Following an uneventful landing, maintenance personnel found that the cause of the problem was that the canon plugs for the propeller synchophaser solenoid for the propeller governor and the auto-feather solenoid for the overspeed governor were found in reverse positions. These two canon plugs are within close proximity and identical in appearance, thus the mechanic must be very attentive when reconnecting these canon plugs. The Service Difficulty Report (SDR) submitter also stated that maintenance personnel had completed an engine change the previous day. It seems apparent that this is when these 2 canon plugs had been reversed. The subject aeroplane is powered with twin PT6A-65B engines and Hartzell HC-B4MP-3A propellers.

In normal operation, the propeller synchophaser sends a pulse voltage to the propeller synchophaser solenoid located on the propeller governor to ensure both propellers are at the same Revolutions per Minute (RPM). When these canon plugs are incorrectly reversed; the propeller synchrophaser control box sends a pulse voltage to the auto feather dump solenoid causing the propeller to momentarily feather.

The submitter also stated that the incorrect connection of these canon plugs could lead to a serious in-flight problem and even more perilously, if a dual engine change was carried out simultaneously.

Propeller canon plugs for the propeller governor and the overspeed governor

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Prop sync connection
Auto feather dump solenoid

Transport Canada Comments:
It is noteworthy that the SDR client submitted this SDR report to prevent other operators from making this mistake. However, all maintenance personnel need to be aware of the possibility of these types of errors and of the possible consequences.

Transport Canada Civil Aviation recommends strict adherence to Canadian Aviation Regulation (CAR) Part V - Standard 571.10 – Types of Work. Additionally, Transport Canada Airworthiness Notice C-010 publication “Inspection of Control Systems” provides necessary guidelines regarding maintenance releases. 

Horizontal Stabilizer Fittings – Level III Corrosion

Beech B200
SDR # 20110727003

SDR submitted:

Maintenance personnel found Level III corrosion at both the upper and lower stabilizer attachment fittings.

The left-hand upper surface of the upper attachment fitting had chaffing and significant corrosion damage at the anchor nut location. Additionally, extensive corrosion damage was found at the lower fitting and at the anchor nut locations.

The same part number 101-620019-1 is used for both upper and lower attachment fittings.

An attachment fitting with significant corrosion damage

* An attachment fitting with significant corrosion damage

Transport Canada Comments:
There are 3 basic requirements for aeroplane corrosion: 2024 material, Aluminum – Anode, and a Copper – Cathode. Basically, corrosion is a complex electro-chemical action that causes metals to be transformed back into their original states. This can lead to a severe loss of metal strength in the part or structure.

A previous SDR reported severe intergranular corrosion and crack fitting in this same area. Always be attentive to the early signs of corrosion such as white/gray powdery deposits and pitting/etching damage, which can eventually lead to crack development.

Hydraulic Fluid Loss

BOEING, 727 227
SDR # 20110730001

SDR submitted:

With the aeroplane on approach, system “A” hydraulic quantity loss was observed and the aeroplane diverted to a station where maintenance was readily available.

Maintenance inspection revealed that the left hand gear door actuator was cracked, allowing the loss of the hydraulic fluid.

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

Boeing 727 left-hand main landing gear door actuator cracked area

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Crack
Boeing 727 left-hand main landing gear door actuator cracked area

Transport Canada Comments:
It is suspected that there was prior evidence for the propagation of the crack on the door actuator through minor hydraulic fluid weeping in the area.

Transport Canada Civil Aviation would like to advise all owners, operators and maintainers to be adamant and thorough when trouble-shooting fluid leaks.  

Tire Tread Separation

BOEING, 737 81Q
SDR #  20110726003

SDR submitted:

On take-off, what was described as a bang was reported to the captain by the cabin crew. No other issues were reported by the flight crew in cruise. Upon landing it was discovered that #2 main wheel received substantial tread separation on its previous takeoff. This caused damage to the inboard flap as well as the inboard spoiler.

Both the #1 & #2 main wheels were replaced and all necessary repairs done to the flap and spoiler making the aeroplane serviceable.

* Boeing 737 main tire tread failure

Transport Canada Comments:
Due to the importance for the correct operation of all aeroplane tires and the seriousness of this event, through the operators internal safety management system, it was determined that the possible frequency of retread could have been the cause of failure.

Therefore a maximum limit of 3 retreads was put in-place for the overhaul of all main tires.

Transport Canada Civil Aviation would like to advise all owners, operators and maintainers of the importance of proper maintenance and inspection of aeroplane tires.

Hydraulic Failure

BOEING, 747 SPJ6
SDR # 20110715004

SDR submitted:

During take-off rotation, the #4 hydraulic pressure caution light came on. The flight engineer reported that the hydraulic fluid quantity went to zero after the gear retraction and quickly after, the airport control tower reported smoke from the #4 engine. The aeroplane returned where it performed an uneventful landing.

Upon the maintenance crew inspection, it was discovered that the relief valve manifold body portion had separated from the hydraulic module located in pylon #4.

As a preventative maintenance action, all other module assemblies were inspected before next flight where no fault was found.

The failed hydraulic manifold was replaced, the hydraulic system serviced and the aeroplane was made serviceable.

Fractured manifold body

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Fractured manifold body
Relief valve

Transport Canada Comments:
It is suspected that the failure of the hydraulic module body was due to the possibly imposed over-torque stress of the relief valve during its last installation, causing metal fatigue.

Transport Canada Civil Aviation would like to advise all maintainers and AMO shop overhaul facilities of the importance to follow all Aircraft Maintenance Manual (AMM) and Component Maintenance Manual (CMM) installation torque values.

Horizontal Stabilizer Attachment Corrosion

BOMBARDIER, CL600 2B19 (RJ100)
SDR # 20110708011

SDR submitted:

While completing a detailed inspection of the horizontal stabilizer pivot fittings per task 55-320-502, iron oxide colored corrosion was observed coming through the fitting halves on both the left-hand and right-hand sides. Upon further inspection, the bushing in the left-hand horizontal stabilizer pivot fitting was found migrated 0.6 millimeters (mm) (0.024 inches).

Both fittings were replaced to correct the fault.

Left hand horizontal stabilizer pivot fitting halves

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Left hand horizontal stabilizer pivot fitting halves
0.6mm (0.024”) bushing migration
Corrosion seen coming through both fitting halves
 

Transport Canada Comments:
The repeat inspection of these stabilizer pivot fittings is set at 48 months or every 4 years. 

Main Landing Gear Trunion Bushing Migration

BOMBARDIER, CL600 2D15 (705)
SDR # 20110223004

SDR submitted:

During a heavy maintenance check, the forward Main Landing Gear (MLG) trunion bushings were found to be migrated on both the left and right MLGs.

The bushings were reseated as per Goodrich Component Maintenance Manual and the aeroplane was made serviceable.

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Upper main landing gear trunion
Flange bushing migration “gap”>

Transport Canada Comments:
Transport Canada Civil Aviation is presently working with Bombardier, the Type Certificate Holder (TCH) of this aeroplane, to address this issue.

All operators and maintainers are asked to pay close attention to this area of the MLG trunion.  

Control Column Wheel - Broken

Cessna 172E
SDR # 20110817005

SDR submitted:

During stall practice with very little yoke aft pressure being applied by the co-pilot (as the pilot was already applying most of the pressure); the control column wheel fractured. Following an uneventful landing, a technician applied a small amount of force on the control column wheel and another portion of the wheel broke off. It was found that the co-pilot control column was made from plastic and had broken in the upper left and lower right corners.

Cessna Service Letter (SL) 62-44 has been superseded by SL 64-8 that calls for a “pull test” inspection and specifies that the critical area is located at the bottom left corner. The SDR submitter stated that this particular aeroplane was out of service for 8 years, thus effects of sun-soaking may have been a factor in this failure.

Broken control column wheel

* Broken control column wheel

Transport Canada Comments:
The FAA has published a Special Airworthiness Information Bulletin (SAIB) to advise operators of Cessna 150, 172, P172, 175, 180, 182, 185, 205, 206, 336 & 337 aeroplanes of the possibility of cracks in plastic or non-metallic control wheels that were manufactured between 1960 and 1964.

Transport Canada Civil Aviation highly recommends compliance with Cessna SL 64-8. In particular, pay close attention to the inside upper corners of control wheels. Any control wheel that has a crack or fails the pull-test should be replaced before further flight with a metallic control-wheel. 

Nose Gear Attachment Fitting

Cessna 182
SDR # 20100928017

SDR submitted:

During routine inspection, the lower nose gear attachment fitting was found cracked behind the nose oleo attachment support.

This aeroplane had previously undergone a major rebuild some 150 hours ago, which included firewall, forward fuselage, nose gear upper attachment fitting and nose gear fork. It appears that the cracked fitting may not have been stripped of paint and subjected to Non-Destructive Testing (NDT) inspection at that time. The fact that the edges of the fitting are clean (no dirt or grime) supports the notion that this is a very recent fracture.

A cracked lower nose gear attachment fitting

* A cracked lower nose gear attachment fitting

Transport Canada Comments:
The nose landing gear not only has to support the aeroplane on the ground but is also subjected to considerable stresses and shock loading during landings.

Owners and operators should closely examine and conduct appropriate inspection techniques. Closely inspect the landing gear area for various adverse conditions (cracks, nicks, corrosion) that can lead to stress concentrations and eventual failure. 

Heater Motor Relay – Burnt

Convair 340 (580)
SDR # 20110701001

SDR submitted:

Following startup of #2 engine; smoke fumes of an electrical odor were detected in the cockpit and continued to build in intensity. The crew shutdown the engine and all aeroplane electrical power including the Direct Current (DC) battery were disconnected. After shutdown, the smoke stopped being produced. Further investigation revealed smoke markings on the right-hand fuselage outboard and above the Alternating Current (AC) panel. The panel was removed; charred relay and burnt electrical wires were found. Location of the relay panel is under the copilot’s windowsill.

A maintenance investigation revealed that an incorrect 25 ampere (amp) electrical relay (part number 1A7S5001) was installed instead of the required 50 amp relay (part number AN3350-2). The circuit breaker in this system is a 60 amp breaker. Avionics personnel repaired the damaged wiring, installed the required 60 amp breaker and returned the aeroplane to service.

A third party had recently completed this heater installation during conversion to a Convair 580A airtanker. Previous aeroplane that had undergone similar conversion were successfully checked for the required 60 amp breakers.

Correct 50 ampere relay - part number AN3350-2 and a Incorrect 25 ampere relay - part number 1A7S5001

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Correct 50 ampere relay - part number AN3350-2
Incorrect 25 ampere relay - part number 1A7S5001

Transport Canada Comments:
All too frequently, incorrect parts are still being installed on aeroplanes. In this case, an incorrect relay rated at only 25 amps instead of 60 amps resulted in a significant safety related event.

It was fortunate that this event did not occur during flight whereby the consequences could have been much more serious.

Flap Ball Screw Actuator – Asymmetric Flap Extension

DHC 8 102
SDR # 20110712003

SDR submitted:

On approach for landing, the crew selected 35-degree flap extension; however flaps abruptly stopped at 15 degrees extension. Following an uneventful landing, the crew noticed the left inboard flap had extended asymmetrical thus causing the flap lower corner to contact and damage a fuselage composite panel. Additionally, the trailing edge of the inboard flap was also significantly damaged.

Subsequent investigation found the cause of this event was due to flap actuator screw jack failure (Time Since New (TSN): 50410, Part Cycles: 47244).

It appears the torque sensor unit would probably not have detected a differential flap torque from the primary flap drive and the secondary flap drive. This is because the primary flap drive would still be turning the worm gear inside of the failed unit, as if all was normal. In this case, even though the now worm gear was continuing to turn, it was not meshing with the now “worn” worm gear on the jackscrew itself and therefore not extending. In the meantime, the other flap jackscrew was working normally and thus extended.

A damaged left hand flap

* A damaged left hand flap

Transport Canada Comments:
The primary flap drive consists of torque tubes connected to the splined drive of a transfer gearbox located in each outer wing. A second splined shaft on each transfer gearbox then drives the flexible secondary drive system that provides continued flap operation in the event of a primary drive separation. The secondary drive will also prevent flap asymmetry via torque sensor unit in the event of the primary drive failure.

Extensive Aileron Control Cable Wear

LEARJET, 45
SDR # 20110713001

SDR submitted:

While doing a “1200 hour” check inspection task of the aileron control cables, extensive cable wear damaged of 40-50% was found within the fuselage run. Cable replacement was carried-out and the aeroplane was made serviceable.

Transport Canada Comments:
All flight control cables are visually inspected at a 600 hour repeat interval, with a 4800 hour cable removal task for a more detailed inspection.

Bombardier Service bulletins SB 40-27-28 and SB 45-27-44 were released last July to address the premature flight control cable wear being found by Learjet 45 operators.

Loss of #2 Hydraulic System Fluid

DHC 8 102
SDR # 20110718003

SDR submitted:

Just after pulling away from the gate for takeoff, a complete loss of #2 hydraulic fluid occurred.

Maintenance personnel removed that rudder assembly to determine the source of the fluid leakage. It was found that the #2 system pressure tube assembly (P/N 82960010-15) had cracked at the bend radius. Additionally, in this same area, #1 hydraulic tube assembly was found significantly chafed (P/N 82960010-103).

Both hydraulic tubes were replaced, #1 and #2 Hydraulic Systems pressure checked and the aeroplane returned to service.

Line reference IPC-27-21-00-15, item 040 with a leaking Line part number 82960010-103

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Line reference IPC-27-21-00-15, item 040
Line part number 82960010-103, leaking

Transport Canada Comments:
This failure is a good example of oil and hydraulic tube assembly problems that are encountered as aeroplanes age in service.

In particular, tube assemblies tend to fail at the bend radius and/or fail due to chafing damage from adjoining parts. 

Wing Spar Crack

EMBRAER, EMB 145LR
SDR # 20110711013

SDR submitted:

During a heavy maintenance visit while performing task card E57-22-00-220-808-2, the right-hand wing lower spar cap was found cracked at wing station 3815 (rib 9).

The crack emanated from the cap edge through a screw for a length of 2.159 centimeters (cm) (.850 inches).

The wing spar cap was repaired as per the applicable Structural Repair Manual (SRM) and the aeroplane was made serviceable.

View looking up on the right-hand wing. Crack on front spar lower cap, part number 145-66736-002

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View looking up on the right-hand wing. Crack on front spar lower cap, part number 145-66736-002
outboard
forward
From cap edge through screw hole

Transport Canada Comments:
Transport Canada Civil Aviation would like to advise all E145 operators and maintainers of this possible defect.