Fixed Wing

Notice / Disclaimer:
Service Difficulty Reports are normally published verbatim. Transport Canada assumes no responsibility for the accuracy or content of any of these reports. Only grammatical or spelling errors are corrected, and content may be reduced as well as personal references deleted.

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AIRBUS A320 - Hydraulic Hose Chafed

A hydraulic hose was found chafed through on Engine 1 green hydraulic system pump pressure transducer of an A320. This resulted in substantial fluid loss, emergency decent and a subsequent unscheduled landing.

Most power plants have a myriad of lines for the various engine and airframe systems, located out of necessity in close proximity to various other lines and components.

The SDR program continues to receive many reports of line failure due to inadequate clearance to adjacent structure. By ensuring adequate clearance and/or protection, both at initial installation and during maintenance, the risk of this costly failure is negated.

 

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BEECH 58P - Flap Motor Defective

SDR # 20030506006

Subsequent to the installation of a newly overhauled flap motor (P/N 3536415157); the AME noticed intermittent flap
indications during functional checks.

Upon removal and investigation of the suspect flap motor; the source of the problem was traced to a faulty/loose internal wire. A further inspection of the flap motor revealed an obvious crack in the gearbox housing.

Transport Canada reminds maintainers to carefully examine all aeronautical parts for defects and also for traceability before installation. The SDR data base lists many other similar reports of this nature.

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BEECH C90A - Anti-Ice Boss Cracked

SDR # 20030115006

During a routine inspection on a Beech C90A, the anti-ice boss on the LH exhaust stack (P/N 109-950000-1) was found broken off with the anti-ice flex tube. The flex tube was also cracked around the lower elbow.

A heads up for maintainers when inspecting this area.

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BEECH C90A  - Anti-Ice Tubes Cracked

SDR # 20021125012

During inspection on a Beech C90A, the R/H engine cowl was removed and the anti-ice flexible tube, PN 90-910100-17 that routes exhaust air to heat the engine cowl intake was discovered cracked. The crack extended approximately 1/3 of the circumference of the tube.

Time Since New (TSN): 124.6 hrs

Manufacturer's Service Bulletin 71-3142 was issued to reduce cracking in this area. However, cracks have been
reported subsequent to compliance with SB71-3142.

Transport Canada recommends increased vigilance in this area for cracks.

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CESSNA 150 - Horizontal Stabilizer Cracking

SDR # 20030423006

Leading Edge Rib assemblies on a Cessna 150, part numbers 0432001-46 & 0432001-6, are very difficult to see. The use of a mirror through the horizontal spar and rib lightening holes is the only way to visually inspect for cracks along the tabs.

The submitter believes the ribs are cracking due to improper ground handling. The practice of pushing the aircraft's tail down by its spar in order to rotate the aircraft in position may be damaging these ribs. Both ribs were replaced with new.

Small aircraft may be moved by hand, however damage can be inflicted on these aircraft by improper procedures. Be sure to use a tow bar.

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DE HAVILLAND DHC 2 MKI - Cable Attach Point Elongated

SDR # 20030318009

During inspection, the elevator torque tube, part number C2T7A, lower cable attach point was found to be elongated.

TSN: 21,878 hours.

Frequently, this sort of defect is discovered only when other maintenance requires the removal of an associated component. Diligent inspection was necessary to turn up this defect that may otherwise have gone unnoticed.

Defects occurring within a cable loop may be indicated by an unexplained change in cable tension or the inability to obtain constant cable tension readings when rigging.

To accurately inspect for this kind of defect, control cables must be loosened in order to detect any play in the attachment ends.

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DE HAVILLAND DHC 7 102 - Wiring Chafed

SDR # 20030514008

During heavy maintenance inspection on DHC 7 102, two wires were found (2610-300 13a22 and 2610-30006a22) chafed and broken at deteriorated clamps in the lower aft firewall area. The rubber cushion had torn away allowing the metal clamp to wear the wires. These wires are for the fire loop system on the #3 engine, which was working when the aircraft was taken down for maintenance. Only the support clamps were holding the wires together.

The fire loop system has been snagged many times in the past; it would fail the pre-flight test three or four times per year, mostly on cold winter mornings. It was usually repaired by cleaning/replacing the connections in the fire loop. It is suspected that the bad connection in these chafed and broken wires may have increased the resistance in the system and caused the test to fail in the past.

This defect illustrates wiring damaged as a result of a deteriorated clamp cushion. It was found during inspection of an aircraft approaching the "aged stage" of its life (20 years).

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ISRAEL ASTRA SPX - Duct Cracked

SDR # 20030424004

During a 1000-hour inspection, the aft baggage compartment interior was removed, allowing access to the ram air duct. This plastic duct is located on the right side tucked tightly against the fuselage skin at STA 350.

During inspection, a 10-inch circular crack was found in the duct (P/N 25W783016011) adjacent to the fuselage skin at approximately Stringer #6R (counting down from upper stringer). The nature of this crack allowed the duct to open up when internal pressure was applied. This crack was only evident by feel, or using a flashlight and mirror.

The duct is used to clear the fuselage interior in the event of in-flight fire/smoke. Replacement of the duct was required.

Israel Aircraft Industries has introduced a new part number duct.

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PIPER PA23 250 - Down Lock Mechanism Failed

SDR # 20030409015

When the pilot selected landing gear up, the gear did not retract. The submitter discovered that the down lock mechanism PN 1764500 was contaminated with dirt. The landing gear was cleaned and lubricated, and gear retractions were successfully carried out. The aircraft was returned to service.

There are many Service Difficulty Reports in the Transport Canada database identifying deficient landing gear cleaning and lubrication. AC 43.13 emphasizes that cleanliness is important during and after lubrication. Cleanliness may prevent unnecessary dirt accumulation and prevent component malfunctions.

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PIPER PA 28 140 - Wing Walk Doublers Cracked

SDR # 20030214006

The doublers on the bottom of the wing walk skins PN 00-62061-002/804 just outboard of the stamped stiffeners were severely cracked. The aft skin crack was 42cm in length. The forward skin had three cracks 5cm in length.

This area is not normally accessible. However, this aircraft (PA28 140) has an extra inspection hole installed from a previous Service Bulletin. The submitter advises that his area be inspected with a boroscope, especially on higher time aircraft.

TSN: 9402 hrs

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PIPER PA 31T2 - Pneumatic Regulator Valve Failed

SDR # 20030313003

On approach of a Piper PA31T2, the crew noticed multiple avionics failures. The VOR signal strength was very weak; #1 radio and most navigation equipment were inoperative. The pneumatic pressure was noted as being at 21 PSI, when it should have been at 18 PSI. The pneumatic regulator valve PN 584228(1H5210) had failed.

This failure caused hot air to be released at the pressure relief valve, which is located in close proximity to an antenna coaxial cable bundle. The hot air hardened and damaged the cables, causing the avionic failures mentioned above.

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SHORTS HARLAND SD 360 - Teleflex Cable Broken

SDR # 20030422002

On approach the pilot could not get R/H engine power low enough for approach power setting. The aircraft landed at a higher than normal power setting and after landing, neither beta nor reverse selections were possible. Maintenance personnel discovered that the power lever movement in the cockpit was limited in the forward direction, and no movement in either direction was visible at the engine.

Investigation revealed that the R/H power control Teleflex cable (P/N A55 2326 Post Mod A8457) had broken inside its conduit. Location of the break was at a 180-degree bend in the cable just below the engine control cam cluster. The problem may have been compounded by the lower cowl interference with the cable conduit when the cowl was in the closed position, causing additional stress in the area of the bend. It was noted that the cowl interfering with the cable would be difficult to see with the cowl closed.

There was no significant damage to the exterior conduit so this defect would unlikely be detected in advance.

This SDR stresses the importance of proper routing and ensuring adequate clearance is obtained with the adjacent structure.