Feedback Issue 2/2009

Fixed Wing

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Damaged Fuel Line

SDR submitted:

After the King Air B200C was towed into the hangar, the maintenance staff were doing a daily inspection and when they had the power turned on for a few moments, noticed fuel leaking from the left hand gear well.

With power turned off, upon inspection, they noted that fuel was leaking from the supply line, which is located between the aux fuel tank and the nacelle fuel tank. On closer inspection, it was noticed that where the fuel line passed through the opening in a bulkhead just forward of the main landing gear, the fuel line was rubbing against the “B” nut of a hydraulic line running alongside it. After removal of the fuel line, a worn area with a crack in the middle of it was found to be the cause of the fuel leak. This fuel line would only



leak if fuel was being transferred from the aux tank to the nacelle fuel tank, otherwise the motive check valve would have closed and not allowed fuel to flow back from the nacelle tank. The pilot had left the aux fuel transfer override switch in the manual position, not the auto position, so that when maintenance turned the power on, the fuel line that was leaking had pressure in it and hence the fuel leaking onto the hangar floor.

The fuel line was replaced and all lines running through this bulkhead were secured and routed to help prevent this wear from happening again.

The submitter added: King Air 200 series aircraft that have incorporated a brake de-ice system and the AVIADESIGN hydraulic gear STC have several lines running through this opening in the bulkhead. Care should be taken when securing these lines to prevent this type of damage from happening.

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AC Power

SDR submitted:

On ground, while the aircraft was being groomed, the AC power dropped off.

When AC power was re-applied, cockpit displays showed AC system in magenta (no communication). The external AC/DC convertor card located in the AC power center had a burned trace. The microprocessor card located above the AC/DC converter card had a small amount of soot but no visible damage. The primary logic card was sooty and when the soot was removed, a small area about 3 square inches was discoloured. AC power center has been replaced to dispatch the aircraft.

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Landing Gear Indicator

SDR submitted:
The landing gear motor control circuit breaker was found popped when the gear was selected down for landing. The gear was lowered by emergency extension indicating three green but the in transit light was still on.

The aircraft experienced a nose gear collapse on landing. Upon further investigation, it was discovered that there were no dividers in the head of the gear down light block. This allowed light from the main gear down and lock light to illuminate the nose indicator. It gave a false cockpit indication that all three gear were in the down and lock position.

A new indicator was installed showing a positive indication of the nose not locked. Two pictures are attached showing the old indicator with all three lights on and the new indicator with only the left and right lit up.

Both pictures were taken in daylight at the same time. They were taken with the nose gear not down and locked.

An inspection of two other same type aircraft showed normal indicators in them with the dividers between the lights.

Transport Canada Comments:
Transport Canada recommends operators inspect during next light bulb replacement.

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Cracked Windscreen

SDR submitted:

During cruise flight the L/H cockpit windshield glass cracked with an explosive bang.



The crew immediately descended and reduced cabin pressure to avoid the possibility of the window glass blowing out. The window was installed on 11 April 2006 and had a total of 177 hours since installation. The aircraft was in the USA at the time of the occurrence and the aircraft was flown to its intended destination. The window was replaced by appropriately rated FAA repair station.

The window will be sent to the manufacturer for warranty and examination.

Transport Canada Comments:
M7 Aerospace, the Type Certificate holder for the SWEARINGEN/Fairchild aircraft, is conducting an investigation to determine root cause for the high number of windshield failures.

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Beech King Air C90 Emergency Exit

SDR submitted:

During an inspection, the submitter found the emergency exit door latch improperly stowed. It appears as though the latch tab had been bent so that the door could be installed. In this configuration, the latch can always (even when pressurized) be opened as the tab passes over the safety plunger. The tab should contact the plunger when pressurized and enter the slot further down the plunger shaft. The plunger should be protruding in the unpressurized mode.

Removing the latch assembly and repositioning the steel tab to correctly interface with the plunger has corrected the problem and the assembly is now serviceable.


IPC 52-20-00-01

The submitter believes that this condition likely existed since manufacture. An inspection of the remainder of the operator’s fleet for this condition revealed no further defects.

Transport Canada Comments:
This defect could potentially have been very serious if it remained undetected! Please be aware of this area at the next scheduled inspection

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Accessory Gearbox - Cracked

SDR submitted:

During taxi to ramp following uneventful landing, an adjacent aircraft reported that fuel was leaking from the L/H engine area of the Boeing 717.

Maintenance personnel found the source of the leak to be a cracked fuel line. OEM engine test bed results revealed that the fuel line leak was due to significant vibrations produced as a result of a large crack on the accessory gearbox. This same fuel line had been changed prior to the event, which confirmed that the gearbox was already cracked beforehand.

Rolls Royce investigation concluded that the wear in the splines of the accessory gearbox radial drive shaft (RDS) was due to a ruptured or missing wear seal and a lack of lubrication. As a result, the OEM has amended the engine maintenance management program to replace the radial drive shaft oil wear seal whenever the RDS is exposed at strip.

This engine had only been in service for some 55 hours and 35 cycles.

Transport Canada Comments:
Any fuel leak must always be thoroughly investigated.

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Nose Gear Trunnion - Cracked

SDR submitted:

During a routine inspection, a technician observed that grease was seeping down the trunnion leg. Upon cleaning and re-lubricating the area, grease was found to be seeping from a 1-inch long, horizontal crack.

During removal of the failed trunnion assembly, the nose gear down assist spring lug broke off. When closely examined, the upper portion of the lug was discoloured. Deterioration of the parent metal may occur if it is not adequately protected from environmental elements.

Transport Canada Comments:
A review of the SDR database revealed several previous cracks in trunnions, most notably at the shimmy damper and R/H upper attachment points. Frequent and detailed inspections of this area are recommended.

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Broken Throttle Cable

SDR submitted:

While reducing throttle levers to cruise power setting following takeoff and climb; it was noted that the R/H throttle would not respond to pilot inputs. The crew carried out a precautionary shutdown of the R/H engine and made an uneventful landing.

While taxiing out to the button prior to the above takeoff, the flight crew had noted that the R/H throttle lever was very stiff. The crew attributed this condition to the throttle friction locks. Upon adding engine power for takeoff, the crew again noted that the throttles were stiff but after hearing a “popping” noise the levers became much easier to advance to the required power setting. As a result the pilot elected to carry out an in-flight shutdown the R/H engine.

Following an uneventful landing, maintenance personnel discovered that the inner element of the throttle cable had completely broken just inboard of the R/H engine pylon bulkhead interconnect.

Transport Canada Comments:
The engine power lever controls in the airframe system to the pylon are not usually disturbed at engine change and usually no rigging is required. However, if the Fuel Control Unit (FCU) or other related component is changed and rigging is required, then be sure that the power lever(s) is free from binding. This is also the opportune time to inspect the engine cable system for defects and condition.

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Restrictor Valve Cracked

SDR submitted:

Maintenance personnel found a No. 2 hydraulic system leak (10 drops per minute) at the union/return line of the Free Fall Selector Valve located in the R/H wheel well area. Retightening the connection did not fix the leak issue. Upon closer inspection, the restrictor valve was found cracked. The restrictor valve was replaced; however the system still had a leak. The ongoing leak was traced to a vertical crack in the threaded portion of the other restrictor valve under the “B” nut. These findings raised maintenance concerns regarding attaching a stainless steel line and “B” nut to the lighter aluminum restrictor valve.

The operator also replaced the hydraulic line assembly.

Transport Canada Comments:
It appears that using two different materials (stainless steel and aluminum) may be a factor in this issue. Overtightening of a nut can cause stress to adjoining lines resulting in stress cracks. Always refer to the Aircraft Maintenance Manual for correct torquing procedures. 

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Rudder Fitting Lug Broken

SDR submitted:

On pushback prior to departure, the crew received a cockpit advisory “No Dispatch Message”. Maintenance investigation found that a portion of the upper rudder airframe attachment assembly had broken completely free, thereby leaving no rudder Power Control Unit (PCU) to airframe attachment at all. The broken portion was still attached to the rudder PCU linkage input arm.

It was determined that the cause of the breakage was due to the absence of the required sliding bushing P/N 170-62218-002, Illustrated Parts Catalogue (IPC) 27-21-05, Figure 01, Item 170. The sliding bushing sits inside the flanged bushing in the lower lug and its primary purpose is to prevent side loads from being applied on the lugs when the large single bolt is installed.

The missing sliding bushing was located in a nearby cavity in the immediate area and was lubricated but showed no “wear” marks. Examination of the single large bolt that connects the rudder PCU to the airframe assembly revealed that the bolt cotter pin was installed. When the bolt pulled through the lower lug, the cotter pin made “scoring” marks on the inside race of the lower lug. The absence of the sliding bushing created “side play” and then overstressed the airframe rudder attachment fitting resulting in breakage.

Log records reveal that recently, a foreign AMO had incorrectly assembled the toggle link that connects the rudder PCU to the airframe attachment fitting.

Transport Canada Comments:
TCCA is currently investigating this potentially serious event with the FAA. Human factors and possible lack of independent flight control checks may be factors in this event.