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September 2014

FIXED WING

Cessna 150: Continental O-200  -  26/06/2014 (201408539)

The engine was overhauled and signed by individual "D" Licenced Engineer and released under ANO requirements.  It was re-overhaul as it had not been done by a Part 145 organisation.  During NDT inspection the crankshaft was found to be racked at the rear of the propeller flanges and also by the oil-slinger. The previous overhauler records were reviewed and it seems to be the crankshaft was magnetic particle crack tested and no defects were noted.  The crankshaft manufacturer does not specify any life limit and it can be re-used after the engine TBO as long as it passes through the visual, dimensional and NDT checks.  We recommend the previous overhauler organisation needs to review his NDT technique methods to ensure he is applying correct current longitudinal and transverse to detect any cracks.  

Cessna 402: Continental O-520 - Nr East Midlands - 02/09/2014 (201412289)

During a normal VFR departure aircraft was rotated normally at 95 knots.  At approximately 50’ the pilot heard a bang and a considerable rise in air noise; speed, direction and climb rate were maintained.  Checking behind him he found the starboard emergency exit door had detached and fallen from the aircraft.  He informed ATC and requested a VFR circuit to land after debris had been removed.  The operator, who was sitting next to the exit that had detached, was unharmed and couldn’t offer any reasons as both the exit handle and the plastic guard were in place, so accidental deployment seemed unlikely.  A normal landing was made without incident.  Airfield Operations recovered the door, no other debris was found. 

Supplementary 26/09/14:  Four retaining clips found to be installed incorrectly causing deployment of emergency exit when subject to airflow.  Retaining clips manufactured and installed and full function checks carried out.  

Cirrus SR20: Continental O-360 - Swansea - 26/08/2014 (201412040)

After two go-arounds during which the nose-wheel made gentle contact with the runway followed by a smooth landing, a red oil pressure warning light went on the MFD screen, having had no prior warning that the oil pressure was falling so was reasonably unconcerned when taxying to park on the apron and shut down. There had been no apparent change in engine note.  A large oil leak was seen and the underside of the a/c was coated in oil with oil flowing from the underside of the engine cowling through the gap where the front wheel strut protrudes. The pilot left a message for his engineers and departed.  The following day there was a large pool of oil beneath the whole length of the a/c.  It was discovered that the oil sump quick-release outer ring was finger tight and that the oil was coming out of the extension nipple.  It should be noted that the addition of a quick release valve with nipple at the base of the oil sump is believed to be a recent modification. The base of the nipple is approx 3 to 3½ inches away from and directly above the nose wheel strut.  There is an indentation on the plastic strut cover commensurate with the strut having risen up and struck the quick release configuration.  The strut itself is secured by bolts to the air frame at the top end and has a rubber bush and stack of dampers to absorb landing impact.  Some play in the strut is necessary.  As the quick release sump valve may be a recent modification, the potential danger might not yet have become apparent.  

Grob G115: Lycoming  O-360 - Wyton - 02/09/2014 (201412366)

Following a couple of visual circuits, the student climbed away using full power, as he retarded the throttle to level off at 800ft, the Instructor noticed the manifold air pressure remained at the full power setting. The Instructor took control and confirmed that the thottle lever had full movement but no effect on the engine settings which remained at full power.  The Instructor declared a PAN and remained at circuit height making a long straight in approach starting at 800ft, slowly descending to 400ft whilst manoeuvring the aircraft using turns to prevent excessive speed.  Approaching the threshold of Runway 08, the speed had increased to approximately 150kts.  Once landing was assured (judged as the threshold passing beneath the propeller hub at 400ft) the Instructor moved the mixture to fully lean thus stopping the engine.  Maintaining 400ft to slow the aircraft down to flap limiting speeds, he selected take-off then land flap, adopting the normal glide approach attitude and landed without incident within the first half of runway 8,251ft runway with enough momentum to taxi off the main runway.  It was confirmed that the nut from the ball stud was missing, which permitted the throttle end of the cable to detach from the throttle lever. The nut was recovered and the threads appeared to be damaged.  There was evidence of material on the ball-stud that was considered to be the stripped threads from the nut.  All aircraft within the fleet (119 aircraft), with the exception of 2 aircraft have been visually inspected.  And there is no evidence of loose nuts fitted to the ball studs on the throttle, mixture or propeller levers in the cockpit on any other aircraft.  The operator directed that until completion of Fleet Check there would be no solo students flying.  Investigation continues iaw Event Reporting Procedure under the Safety Management Plan.  

Jodel  DR1050: Continental O-200 - Nr. Conwy, N. Wales - 17/06/2014 (201408027)

While returning a large increase in noise and reduction on power was experienced. Valley Radar was contacted, PAN call made and 7700 set. The a/c was maintaining height and the engine producing power with good oil pressure but considerable exhaust noise and no smell of burning so the decision was made to cross the high ground and make towards a disused strip.  The engine was showing no sign of worsening at a constant throttle position so, avoiding towns, the a/c maintained height and returned to a successful landing with emergency services in attendance. The cowlings were removed and a 60 mm by 45mm piece from the front of the exhaust manifold was missing.  This piece was from a formed and welded part that provided a flow curve from the vertical exhaust port to the horizontal manifold.  The fractures were both along welds and across the material. There was no evidence of any repairs or major corrosion. The design of the manifold is such that the exhaust pipe exit is in cantilever and not supported, thus the load of the exhaust must pivot about the rear exhaust port and possibly place a vibrating stress on the front port connection. The steel exhaust material is thin and once structural strength is lost further cracking failure will be rapid.  

Roko Aero NG 4HD: Rotax 912 - Bagby, Thirsk - 08/09/2014 (201413155)

Annual inspection found rudder very stiff with heavy  corrosion on lower bell crank assy.  When rudder was removed water poured out.  Manufacturer informed and on advice removed bell crank to clean/repair, seal bell crank and rudder tube.
(Note) rudder found to hold 4 litres of water in 'D' box. Manufacturer has forward a drawing to drill drain holes.  All info sent to surveyor.  Reporter does not know if/how manufacturer intends to clear this fault on a broader scale.
(GASCo Comment: manufactured in 2009/10).   

Partenavia P68: Lycoming O-360 - Liverpool - 18/08/2014 (201411489)

Returning from a survey flight, a section of the left spinner was found to have become missing during the flight, with nothing unusual seen.  Some damage had occurred to the cowl area around the air intake as a result of the departing fragment(s). Failure is one of a number that during at least 5 years.  Manufacturer is aware via information, photographs and video. Propellers dynamically tested, with no issues detected.  There have now been 2 recent failures, including this incident.  Post-flight inspection of the spinner is carried out, as well as the pre-flight inspection, by pilots and it is checked at every 50hr inspection by maintenance staff.  Information was sent by our AWS to the Type Liaison Surveyor in Feb 2013, for possible further contact with those responsible for propellers at EASA, but we have heard nothing. In Jan 2013 Manufacturer wrote, 'I have began conversations with Engineering to see what if any fix we can offer on this issue.' Manufacturer has not communicated any 'fix' to us.  

Partenavia P68: Lycoming O-360 - en-route  - 07/09/2014 (201412816)

Two hours into flight, camera operator noticed CO detectors had turned black, they were yellow before the flight.  Windows opened and P1 hot air vent was closed, even though no air was felt coming from it.  Checked each other, both felt OK.  Over the sea at the time, approx 1 hr to run, decided against turning back and  continued to monitor the CO detectors in flight, little change and kept checking each other. Both felt OK and kept the windows open and kept conversation going,. Continuing the flight as normal.  Went to hospital for checks, small traces of CO found in both crew members' blood, but not enough to require further treatment. 

Ingress was due to failure of the exhaust manifold (exhaust stack p/n 6.1009-9) which slots inside the exhaust muffler, stack was cracked at the point of overlap with the muffler.  When investigated, the stack moved, without much resistance, in and out of the muffler as the exhaust clamp (p/n 6.1027-2) is broken.  At the time of investigation, it was cracked, removing it caused it to fail completely. The hole(s) in the stack are to allow a pin (fixed to the clamp) to be inserted to prevent the stack/muffler from rotating.  Servicing requirements are: Minor Inspection (every 50hrs) calls for a check of attaching flanges at exhaust ports on cylinder for evidence of leakage.  SB83 requires inspection of the exhaust mufflers every 200hrs. 100hr inspection of muffler and heat exchanger for cracks and security. The failure of the exhaust system at this point does not allow CO into the cabin ventilation directly, it will have entered through other means, i.e. any holes through the leading edge, door seals, etc.  While examining the system NJ turned the aircraft with the failed exhaust system downwind, and the CO sniffer readings dropped from 40ppm to 9ppm, indicating that there is no direct route for exhaust fumes from the point of failure to the cabin.  Due to recent CO issues, the pilot checklist has been amended to ensure that CO detectors are checked during flight. The changes will take effect through introduction of the Company's EASA AOC manuals in October. However, pilots are aware of the issue through Company Digests, Flight Safety Meetings and feedback from previous events.    

Piper PA31 Navajo: Lycoming TIO-540 - 18/06/2014 (201408002)

During Annual Check, the fuselage lower forward section inspection carried out, both left and right spar attachment bulkhead assemblies part number 44758-000 and part number 44758-001 were found to have crack damage.  The damage was limited to the bulkhead only and did not continue into any additional structure. Manufacturer contacted and manufacturers approved repair supplier, enabling removal of the damage material and install re-enforcement to restore strength. Further inspection on a second PA31 revealed same area cracked.  It is known a further twenty PA31-350 aircraft have had the manufacturers repair carried out.  

Piper PA34 Seneca: Lycoming O-360 - Alderney, Channel Is. - 29/08/2014 (201412041)

The aircraft was pre-flighted by the pilot and the nose baggage door checked, with the key removed and the handle indicating the locked position.  There is an interlock mechanism to prevent the key being removed when the handle is in the open position.  Shortly after rotating the nose baggage door flew open, as there was insufficient runway remaining to stop he elected to carry out a circuit; a safe landing was made. The door flapped around in flight and broke itself up but no damage was caused to the rest of the airframe.  The airflow was badly disturbed causing rapid pitch changes. Inspection after landing showed that the handle was in the locked position and the key had been removed.  No reason was found for the door having come open. This aircraft type suffered from a number of these occurrences before the modified interlock mechanism was retrofitted.   A post-incident runway inspection revealed no FOD.  

Schleicher ASW28 18E: Kleinmotoren 2350 -  Portmoak - 03/08/2014 (201411465)

During daily inspection and whilst investigating de-compressor issue, crack on left hand mount detected. Engine had run roughly on last flight and previous daily inspections had not detected propagating crack, a cable tie may have partially hidden developing problem.  Subsequent crack detected on rearward fuel pump support bracket plate extending outward from drilled mounting aperture, forward fuel pump mounts OK. Last ARC checklist identified no faults found-section 63.  Front HT lead replaced during ARC as previous to review engine had been running only on one cylinder during last flights. Vibration source?  April 2013 aircraft landed with engine extended and wheel up.  Inspection and rectification had been carried out, no report of pylon damage.  

Schleicher ASW28 18E: SOLO: Cardiff - 20/08/2014 (201412458)

Third occurrence of pylon cracks (first reported 25 March 2014).  There does not appear to be any maintenance instructions or  guidance on installing the engine or anti-vibration mountings plus the pylon on the two aircraft appear to be of an early design, the instruction from the manufacturer is to install alternative pylon as a replacement.  The BGA is extremely concerned that an in-flight failure of the engine pylon could be catastrophic as the propeller is located just above and to the rear of the pilot this being an engine on an extending pylon. A cracked pylon is an unsafe condition. The reporter believes there should be additional maintenance and inspection guidance for the engine mountings and pylon with consideration given to replacing pylons of a later design that do not appear to have the same issue.  BGA has advised owners not to use the engine until an improved pylon is installed or issue resolved by the manufacturer. Urgent action is required by the Type Certificate Holder before there is a further occurrence by issue of a Technical Note (Service bulletin). Investigation under 201403574.  

Schleicher ASW28 18E SOLO: Cardiff - 23/08/2014 (201412459)

Fourth case exactly the same as previous reports of pylon cracks on the type (first reported 25 March 2014).
Investigation under 201403574.  

Tecnam P2006T: Rotax 912 - Gloucestershire - 17/09/2014 (201413198)

During the morning "A" check, evidence of heat/smoke was discovered on the side and edge of the stud engine nacelle. Upon removal of the stud engine cowlings, the rear left exhaust pipe/header was found to have completely failed near the cylinder head. The pilot, who also discovered the problem, reported no abnormal engine conditions or heavy landings. Possibility of a fire had the failure occurred at a high power phase of flight such as the take-off or climb.  Upon inspection of the engine bay the Rear left exhaust header was found to have failed in close proximity to the cylinder head. The part is manufactured by welding the pipes to a common stub pipe which fits in to the cylinder head, failure has occurred in proximity to this welded joint.  There are reinforcing plates bridging these joints, they have also failed.  Due to the nature of the exhaust system (Sprung) the forces acting on the pipes have pulled the two broken sections apart slightly allowing exhaust gas to leak. Due to the known issues regarding the P2006T exhaust systems, they were carefully checked at the previous 50 hour inspection and found to be satisfactory. The Engine bay remains damage free and there is a minimal amount of smoke evidence suggesting that the failure occurred in the final stages of the previous flight and there has been no prolonged use of moderate or high power post-failure. The Technical Dept. at Tecna have been informed and the part has been photographed and returned to them for analysis.  

SINGLE ENGINED ROTARY WING

Aerospatiale AS350: Turbomeca Arriel - Derry Lodge - 20/06/2014 (201408101)

On the way to pick up water during a fire fighting operation, the cargo hook released and the empty Bambi Bucket dropped to the ground. Air speed: 70kts; Wind: SW10-15kts; light turbulence. The flight path had been selected not to overfly third party property or any persons.  Operation was terminated, Operations Department informed and the aircraft was flown back to base.  Engineering was informed and the aircraft was checked, finding a broken part on the release cable.

Supplementary 03/09/14: The cargo hook was fitted to the aircraft for Forestry Operations. This has to be used because of its fore and aft orientation and load cell modification. It is compatible with normal load operations but the manual release cable is a known weak point and a reason behind upgrading to another type of cargo hooks which are now standard fit on fleet aircraft. The manual release cable failed at the ferrule where the outer sheath enters the cargo hook just above the lock nut. It is not known if the cable was subjected to excessive external force or had formed an incipient crack prior to the failure either in use or in ground storage. Although sensitive to good cable routing nothing was noted on inspection that would suggest poor routing leading to tension on the assembly. A new ferrule was fitted and the release cable tested satisfactorily.  

Hughes 369: Allison 250 - Lustleigh - 29/08/2014 (201412317)

Cracking found on three rotor blades during inspection.  Information Letter received from manufacturer reference fatal accident due to blade failure on this aircraft type.  On Check A, identical blade cracking found on three of the five main rotor blades.  Aircraft now grounded awaiting manufacturer's input.  

Robinson R44: Lycoming O-540 - Sherburn-in-Elmet - 22/06/2014 (201408327)

The aircraft was being refuelled, the fuel operative being an unlicensed engineer commend on the cleanliness of the aircraft to the Ops Manager who was cleaning the windscreens.  The Ops Manager commented on the issue of loose cut grass which causes it to stick with pollen to rotors and the screens/airframe. The fuel operative then apparently walked around the aircraft announced that a tail rotor blade was scrap!  The Ops manager contacted the operator (Accountable Manager) who attended within 15 minutes. The AM took a magnifying glass to the blade tip and stated no flight until a second opinion from a licensed engineer. Aircraft  grounded, although the pilot checked the aircraft meticulously he failed to see the tiny erosion hole. 1) The condition of both tail rotor blades was noted on annual inspection, although within limits it was agreed to be excessive for the component hours. The AM was made aware of this. 2) The alleged hole was not apparent the day previous. 3) On further inspection it appears possibly to have been masked by pollen build up and is not penetrating the tip of the leading edge. 4) The AM expressed surprise that this could be seen at all without pre-knowledge. 5) The aircraft was due inspection at 765.5 hours.  

Robinson R44: Lycoming O-540 - En-route - 20/07/2014 (201410265)

Throttle failed.  Initial investigation by air crew revealed that the fuel control (11) mounted throttle bell crank (1) appeared to oscillate in a lateral plane whilst the throttle was operated. Normal operation of the throttle bell crank (1) is in a fore and aft plane. Inspection by engineering staff revealed that:  
Palnut (10), Nut (9) and spacer (8) were missing. Nut (9) and spacer (8) were found in the engine bay. Bell crank (1) and remaining bell crank hardware was inspected and found satisfactory. Bell crank (1) was refitted and a replacement palnut (10) was installed; • Bolt (4) was installed with incorrect orientation i.e. the bolt head was  fitted adjacent to rod end (12). The rod end bearing was found to be pushed out of the rod end housing. Rod end was replaced and remaining hardware was inspected and refitted. Annual inspection was completed on 29th January 2014 at 1831.5 hours. The engine was refitted at 1816.3 airframe hours following overhaul due to an overspeed.  

Robinson R44: Lycoming O-540 - Blackpool - 03/09/2014 (201412464)

During an unscheduled maintenance input to investigate engine oil leaks, the engine rocker covers were removed. The exhaust valve stem cap for the number 3 exhaust valve was found resting on the cylinder head. The valve train had been dis-assembled 11.1 hours previous to facilitate the replacement of the exhaust rocker push rod and tube.  No 3 Cylinder valve train dis-assembled and inspected.  Hydraulic tappet had collapsed. Push rod tube seals replaced due to leak. Valve train re-assembled.

 

 

 



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