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May 2014


Robin R2100: Lycoming O-235 - Bournemouth/Hurn - 23/03/2014 (201403630)

When starting aerobatics towards the end of a local flight there was a small of burning rubber or plastic.  There was no smoke and CO monitor was normal, but many instruments failed and circuit breakers for battery and alternator popped out. Pilot tried resetting the alternator breaker without a problem, then that for battery, leading to both breakers popping out again. This left a choice of immediate flapless forced landing at local gliding site if fire broke out or attempting to return without RT and transponder.  Commenced descent, but after one minute with no smoke or further smell, considered that odour was due to burn out of insulation due to short circuit, and that circuit breakers had prevented development of fire, so called ATC on mobile phone. Tried to explain that I had lost all electrical power and hence RT/transponder and that I wished to return via nearest entry point and would require red/green signalling lights.  Owing to engine noise almost impossible to make out reply, but understood that my request had been accepted.  On reaching ATZ failed to see either red or green lights, but as it was a quiet Sunday entered and joined downwind as per normal keeping a very keen look out. Saw a large plane on long finals, and believing that I would have priority over most traffic made a hurried phone call to ATC saying that I was going to slot in behind the 737.  I did not hear a reply and seeing no other following heavy, positioned to approach at minimal safety separation to be a reasonable distance ahead of any other light aircraft that I might have failed to see if priority assumption incorrect.  Descended above glide path indicated by PAPI for flapless landing.  As I had not seen any red/green lights I phoned ATC to explain my actions and was told that I had been given a green light.  Failure to see light attributed to combination of bright sunlight and my dark sunglasses.  Examination of aircraft showed that the exhaust muffler shroud had disintegrated leading to burnout of wiring associated with the alternator.  

Beech 200: P & W PT6 - Farnborough - 13/05/2014 (201405993)

During phased detailed structural inspection using a boroscope, it was found that x22 rivets were formed on top of and through previously installed rivets.  This is outside of standard riveting practices and it is assumed that the rivet holes in this location will be figure of 8 damaged and over acceptable limits if the rivets were removed. The elevator and coving skin have been removed for further inspection, a report has been raised and sent to manufacturers repair design office for the raising of a field repair and possible temp inspection/repair that might enable the aircraft to return to operation with a permanent repair to be carried out at a later date.  

Cessna 421: Teledyne 520 - En-route - 21/02/2014 (201403316)

Aircraft returned due to elevator trim failure.  During final stage of a 1task conducting environmental data gathering, in clear air with good visibility, the AP trim alarm sounded. AP disconnected.  Investigation revealed that the electric trim would not motor when initiated via pilot trim switch. Trim CB reset, no change. Manual trim wheel appeared locked in position.  One passenger briefed on situation and requested to remain seated with belt fastened for remainder of flight.  Control check carried out.  Descend requested from ATC for normal return to home/maintenance base.  Reduced speed and ROD profile completed initially.  Passing approx FL200 manual trim stiff but usable, passing approx FL150 manual trim free and moveable through practical range.  Normal descent and recovery completed.  Engineering assistance sought from Part 145 company.  Fault investigation carried out.  All elevator trim control cables checked for tension/freedom of movement, found satisfactory.  Electric trim fault traced to 55x autopilot comp / programmer.  Unit removed and sent for repair.  Returned repaired unit re-installed and op checkout of elevator trim carried out satisfactory.  

Diamond DA40: Thielert Centurion 1.7 - Sherburn-In-Elmet - 18/05/2014 (201406235)

Aircraft departed VFR 1 pob, shortly after pilot declares Mayday, and requested an immediate return.  Aircraft given surface wind as RW 32 did not seem an option. Captain then requests diversion with an initial vector, the A/C was observed slowly descending.  The pilot detailed the problem, increased RPM, warning lights, and a rough running engine which was losing power. Latest information passed to the pilot at which point he stated he would not make airfield and had chosen an Airstrip 3 to 4nm west of diversion airfield.  A/c landed safely.  
Supplementary 27/05/14:  After a normal departure and the pilot initiated a further climb when the rpm rose to the red zone and the pilot reduced the power setting to reduce revs.  He then got first ECU A FAIL and shortly after ECU B FAIL.  At this point he called Mayday and with the rpm continuing to be “uncontrollable” made a successful landing.  After landing he reported a good deal of oil on the lower airframe and the gear box inspection window empty. 

Supplementary 29/05/14: Union on the end of the above pipe was found to be cracked allowing the gearbox oil to deplete during the flight. Engine manufacturer advised of the failure.

EXTRA 300: Lycoming 580 - Northampton/Sywell - 07/05/2014 (201405784)

The aircraft was being flown as Number 4 of a 4 ship formation aerobatics training sortie. During a formation move, it was noted that movement of the throttle lever had no effect on the power being delivered by the engine.  In accordance with Company Standard Operating Procedures the aircraft was safely manoeuvred away from the other aircraft in the formation, and positioned toward Hi-Key.  Whilst positioning the aircraft towards Hi-key a 'handling check' was carried out which established that the throttle lever was not controlling the engine and that the power was fixed at 27 inches of Manifold Air Pressure: a power setting too high to affect a safe recovery and landing with the engine running.  Having positioned the aircraft above Lo-key and when sure of being able to achieve a safe landing, the engine was shut down. The aircraft was landed safely.  This was a serious emergency that was commendably handled by the pilot resulting in a safe outcome.  Following an investigation by the Part 145(M), it was established that the cause was the failure of the throttle cable. The throttle cable is a metal rod, protected by an outer sheath that connects the rear throttle lever to the fuel injection throttle body. The metal rod had sheared approximately where the throttle cable passes through the firewall bulkhead.  No visible damage or kink could be identified in that area. The aircraft has less than 500hrs total and the cable had not been disturbed since it was installed at manufacture. The Part 145(M) has extensive experience maintaining these aircraft and has not seen or heard of this failure before. The aircraft manufacturers were informed immediately, who stated that there are no previous records of this type of failure.  Being a sealed cable, it is impossible to check the status of the other aircraft in the Company’s fleet. However, the fact that this issue has not been seen before in a large worldwide pool of aircraft would indicate that it is either a one off or of extremely low likelihood.  As such, the Company have recommenced flying the other aircraft within its fleet. The Company’s investigation and subsequent reporting process remains open and will conclude in due course.


Agusta A109: P & W PW200 - Northampton/Sywell - 29/04/2014 (201405433)

During an 'A' check the main rotor rotating scissor link, upper link bushings were found to be severely worn. The bushings on the upper scissor link support flange were also found to be worn. Black/brown residue (dust) was found indicating heavy fretting. The Teflon coating on the opposite bushing had delaminated from the metal part of the bushing, so it is thought this occurred on the other bushing, resulting in metal to metal contact, leading to excessive wear and damage. The top-hat section of the bushing has been totally worn away leaving a gap of 2.2mm and abnormal play in the main rotor rotating scissor link assembly. The Upper Scissor Link was replaced as a complete item, i.e. Teflon bushings installed from manufacturer, 70.2 flight hours. Main rotor rotating scissor link and upper support flange have been removed from service for
replacement with new items.

Eurocopter EC135: Turbomeca Arrius - Thruxton -12/05/2014 (201405983)

When preparing the A/C engine wash rig for the daily wash, there was just under half a container of water.  To prevent waste, water is poured from other used containers into the one to be used. Normal engine start carried out, coming to the end of the wash, both the A/C engines were heard to increase in speed, this was also confirmed by the engine instruments. I attempted to shut down both engines with the switches. The engines continued to run so shut down by manual throttle was immediately carried out. Paramedic who was connected to the long intercom lead was also stating that smoke was coming from the engines at the same time as I was shutting the engines down. Both engines once closed down were vent run to reduce their temperature. Ops and engineering informed. On smelling the water container it smelt of fuel as did one of the water containers that I had topped it up with (approximately 1 litres) The wash had used all the water and the fuel being on the top had then been pumped into the engines causing the run up. Waste fuel had been put into one of the old water tubs rather than the dedicated marked contaminated waste fuel container, and when topping up the container the pilot had not checked it was water or smelt any fuel. On inspection of the Engines, No2 Engine found to be seized. Engine manufacturer contacted for advice, No1 Engine to be replaced along with the No2 engine due to possible high temperature internal damage. Aircraft road transported to maintenance facility for both engines to be replaced. Company Safety Event Investigation initiated and is on-going.  (GASCo Comment:  A very expensive error in procedures.  Many years ago a German Operated BAC1-11 crashed shortly after take-off from Hamburg after a double engine failure due to the de-mineralised water used on take-off, containing fuel.  In the subsequent forced landing on a road 22 of the 121 occupants were killed).   

Eurocopter  EC135: Turbomeca Arrius - Manchester/Barton - 24/04/2014 (201405277)

After closing down the aircraft and carrying out a rotor head inspection, the pilot detected a stronger than usual smell of fuel. On carrying out a detailed inspection in and around the aircraft I found, on the bottom of the Number one engine bay that there was fuel present.  Engineering and operations were contacted. The Nr1 Engine prime pump was turned on and the engine motored on a Vent run.  Fuel leak was traced to Nr1 Engine HMU. Nr1 Engine HMU replaced law EMM 73-23-00-900-801-COl.  Ground run carried out iaw EMM 71-02-13-280-801 and Ground Power Check carried out iaw MSM 05-62-00, 6-3 F(22).  Aircraft returned to service.

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