Rotorcraft

Aerofilter Installation Chafe

Aerospatiale, AS350 B2
(SDR) # 20121207004

SDR submitted:

While conducting a "T" inspection on an AS350 B2 with an FDC aerofilter assembly installed, a crack was found in the fiberglass. The fiberglass was worn on the aft flange where upper housing part number (P/N) 1350A3-1 contacts lower housing P/N 1350A4-3. The lower housing caused chafe damage to the upper housing. If not detected, the aft flange could have completely worn through and gone into the engine.

Upper and Lower housing chaffing

Transport Canada Comments:  

A heads up to maintainers that have this STC installed to pay attention to this area during installation and inspection.

Collective Potentiometer Intermittent

Aerospatiale, AS350 B3
(SDR) # 20130510004

SDR submitted:

On a flight just before a fuel stop, the yellow governor light illuminated on the master caution panel.

The pilot landed without incident.

After discussion with the pilot about the fault code and the power being cycled on the aircraft, as there was no sign of the yellow governor light or fault, he returned to base.

Upon returning to base, the collective was looked on the VEMD (Vehicle Engine Multifunction Display) and it showed a consistent signal throughout the range of travel. It flew approx 3.5 hours with no further incident from the initial fault.

The part was replaced once a new one was obtained.

Collective potentiometer assembly

Transport Canada Comments:  

Eurocopter issued Alert Service Bulletin 76.00.18, which introduces a modification to eliminate the potential for a rotor RPM drop in-flight. The modification involves reconditioning the electrical harness that connects the engine computers digital engine control unit (DECU) to the engine anticipator potentiometer, in order to eliminate any over-length and loops from this electrical harness. 

Instrument Panel Bundle Chaffing

Bell 412 CF
(SDR) # 20130128024

SDR submitted:

A pilot reported lateral cyclic impulses was felt in all flight regimes when the autopilot was on. Extensive trouble shooting was carried out over a 3 week period. The final rectification of the problem was the replacement of wire C943D22 which was found chaffing on the aircraft structure under the instrument panel on the left-hand side. The wire that was replaced was found in wire bundle K-TJ3-4B which was part of the EFIs modification.

A test flight was carried out serviceable and the aircraft was returned to service.

Wire bundle chaffing under the instrument panel

Transport Canada Comments:  

Very difficult defect to locate. The operator added that the rest of the fleet had been inspected with no similar defects discovered. 

Landing Gear Extension Failure

Bell 430
(SDR) # 20130430014

SDR submitted:

An aircraft was on approach when the pilot attempted to extend the retractable landing gear and did not obtain a green advisory light for the left-hand (L/H) main landing gear.

After 5 attempts with the primary landing gear handle, the pilot decided to pull the emergency gear handle with no result.

A second passenger onboard riding in the copilot seat who happened to be a pilot was able to contact maintenance personnel by phone. While in a hover, the passenger was able to exit the aircraft from the copilot’s seat and locate an aircraft jack. With the nose gear and right-hand (R/H) main gear fully extended and locked, the pilot was able to rest both wheels on the tarmac with power on while the passenger was able to get the aircraft jack positioned under the L/H aft jacking point with the pilot keeping the aircraft light on gear.

Once the aircraft jack was positioned, the pilot was able to rest the aircraft on two extended gears and the jack then successfully shut the aircraft down.

An Aircraft Maintenance Engineer (AME) arrived and determined that the L/H wheel brake hose part number (P/N) 70-012F000D210 was hung up on the down lock actuator P/N 222-336-001-105 not allowing the L/H gear to extend. The AME was able to free the brake hose and extend the L/H gear.

The operator took the following corrective actions to prevent a reoccurrence:

The L/H and R/H brake hoses were replaced and the hoses repositioned to prevent interference, heat shrink was installed on the hose with chafe tape on the landing gear strut to prevent chafe and adel clamp along with the hose repositioned to prevent future fouling. The gear was swung on jacks several times. The aircraft was returned to service.

Hose part number 70-012F000D210 got hung up behind this bracket attached to part number 222-336-001-105 downlock actuator.

Installed heat shrink on brake hose and installed chaffe tape to the main landing gear as part of corrective action. Reversed adel clamp to allow for additional clearance as part of corrective action.

Transport Canada Comments:  

This incident illustrates the importance and vigilance of routing and proper security of hoses and clamps in vital aircraft systems. Failure to do so may have catastrophic consequences. 

#1 Bearing and Driveshaft Damaged

Eurocopter France, EC130 B4
(SDR) # 20110222012

SDR submitted:

The helicopter was parked outside with all the necessary covers and heaters installed. There had been blowing snow for the past day prior to this incident. For the first flight of the day, the helicopter was ground run and positioned closer to where the passengers were to be picked up. This flight took 30 seconds. After this short flight the pilot reported that there may have been an unusual vibration therefore helicopter was inspected. The Aircraft Maintenance Engineer (AME) discovered that the #1 bearing and driveshaft were damaged. The rear shaft had contacted the Fenestron and a rub mark was evident on the shaft. The #1 bearing attachment bracket was loose and holes had been worn oblong. The helicopter was brought inside a hangar and the horizontal stab was removed and it was discovered that the bulkhead under the #1 bearing was cracked approximately 15.24 cm (6 inches) long. There was evidence that water had entered the hollow drive shaft and caused this vibration and subsequent damage. Approximately 15 ml of water was collected after the snow had melted from the rear end of the shaft.

Transport Canada Comments:  

The investigation determined that blowing snow did enter the driveshaft and caused an imbalance of the driveshaft which in turn caused this damage. 

Pilots and AMEs should be extra vigilant in inspecting this area during the preflight and take necessary precautions to prevent any moisture from entering the driveshaft (plugs, covers etc) 

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