News & Comment

What a Difference a Hole Makes: E-8C JSTARS $7.35 million Radar Mishap

Posted by on 11:24 pm in Accidents & Incidents, Fixed Wing, Human Factors / Performance, Maintenance / Continuing Airworthiness / CAMOs, Military / Defence, Safety Management, Special Mission Aircraft

What a Difference a Hole Makes: E-8C JSTARS $7.35 million Radar Mishap While washing a USAF Northrop Grumman E-8C JSTARS  at a the Northrop Grumman Lake Charles Maintenance and Modification Center in Louisiana, maintainers covered up three drain holes in the 40 ft (12 m) canoe-shaped radome.  This houses the 24 ft (7.3 m) APY-7 passive electronically scanned array Side Looking Airborne Radar (SLAR) antenna fitted to the heavily modified Boeing 707-300 surveillance aircraft. So far so good… Unfortunately these were not uncovered afterwards says a Air Force Materiel Command (AFMC) Accident Investigation Board (AIB) report. It is reported that: …maintainers were required to make sure the drain holes weren’t obstructed as part of the pre-flight inspection process… But pre-flight inspections were conducted four times [at Lake Charles]…without catching the drain hole obstructions. The damage wasn’t caught until the JSTARS was flown back to Robins and maintainers there conducted their own inspection. The AIB describe this as being due to a “checklist error”.  Consequently 4.5 in (114 mm) water collected in the radome between 4 June and 27 July 2016. On 25 June 2016, Northrop personnel powered the aircraft’s radar as part of maintenance procedures, cycling the antenna. The combination of electrical current and moisture exposure led to the degradation and damage of many of the antenna’s components, to include 240 circuit cards. This caused $7.35 million damage. Most of those components had to be replaced. Four other aircraft were subject to inspections.  It was later reported that one management change had been made at the lake Charles facility.  It was commented that: …problems stem at least partially with the Air Force’s confusion over when and if to retire JSTARS. When the service planned to retire the fleet, it kept aircraft from moving into depot maintenance, believing that no further work would be needed before they were mothballed. However, after it decided to keep operating JSTARS, a higher number of planes than expected were rushed to the depot [creating an]…unexpected demand. Improperly installed bolts are also reported to have been found. It was reported subsequently that: Oversight processes had also been relaxed, so maintenance work was not as heavily scrutinized as it had been on previous contracts.   …the Air Force has since added some layers of inspections, while Northrop improved training and quality control processes. The parties also modified the incentive structure on the contract to balance capacity and quality, which had languished. A Northrop Grumman spokesperson said: As we had gone through trying to get more airplanes through the depot, we had kind of shifted the incentive to be more on how fast we were able to get them through.  Never was it anybody’s intentions … on the part of any of us to sacrifice quality for speed, but unfortunately I think we saw some of that. Other Safety Resources Professor James Reason’s 12 Principles of Error Management Back to the Future: Error Management Safety Performance Listening and Learning – AEROSPACE March 2017 Maintenance Human Factors: The Next Generation Airworthiness Matters: Next Generation Maintenance Human Factors Lost Tool FODs Propeller Blade, Penetrating Turboprop’s Fuselage Micro FOD: Cessna 208B Grand Caravan Engine Failure & Forced Landing B1900D Emergency Landing: Maintenance Standards & Practices Robinson R44 Power Loss: Excessive Lubricant United Airways Suffers from ED (Error Dysfunction) USAF RC-135V Rivet Joint Oxygen Fire: A military accident investigation has paradoxically determined that a $62.4mn fire...

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USAF Parachutist Fatally Extracted Through Ventilation Door

Posted by on 10:14 pm in Accidents & Incidents, Fixed Wing, Human Factors / Performance, Military / Defence, Safety Management, Special Mission Aircraft

USAF Parachutist Fatally Extracted Through Ventilation Door (Shorts Skyvan N46LH) On 21 February 2014, a US Air Force (USAF) Tactical Air Control Party Jumpmaster died during an inadvertent parachute extraction from a contracted Short SC-7 Skyvan N46LH, operated at SkyDive Arizona over Eloy, AZ. The fatally injured “mishap jumper” (MJ) was wearing an MC-4 ram-wing parachute.  He was a member of the 17th Special Tactics Squadron, Air Force Special Operations Command (AFSOC), assigned to Fort Benning, GA. According to the USAF Accident Investigation Board (AIB) report: En route to the drop zone with the mishap aircraft approaching 9,700 feet mean sea level, the MJ stood and gave the “10 minute” warning and winds call, followed by the “don equipment (rucksack)” command. The MJ opened the Plexiglas ventilation door between the aft cargo door and aircraft floor and sat down on the seat next to the door to don his own rucksack. [It is not clear if he] inadvertently attached his rucksack to the ripcord handle, snagged it on equipment, or inadvertently grabbed [the handle].  [Shortly after] the MJ leaned forward, the spring-loaded pilot chute popped up and fell directly through the open ventilation door taking the reserve parachute with it. In roughly two seconds, the MJ was extracted though the ventilation door opening-tearing off his rucksack, damaging the aft cargo door, and killing him instantly. The MJ landed under a fully inflated reserve parachute …southeast of Eloy, AZ. The investigation concluded that the MJ inadvertently pulling his reserve parachute ripcord while donning his rucksack.  The open ventilation door, was of “sufficient size for a parachute to pass through, but not large enough for safe passage of a person”.  Opening the ventilation door without also opening the cargo door “did not violate either military or civilian guidance” but was considered contributory. …testimony varied on whether the hazard of an inadvertently deployed pilot chute departing through the ventilation door was briefed as a safety hazard, it appears the personnel interviewed largely failed to identify or underestimated the risk of opening the ventilation door… Investigators also noted that: The characteristics of the MC-4 equipment attachment D-rings, which are similar in appearance, feel, and location to the lower portion of the ripcord handles, make it relatively easy to either (1) attach equipment inadvertently to a ripcord handle instead of the D-ring, or (2) catch equipment inadvertently on ripcord handle while attempting to attach equipment to the D-ring. Safety Resources James Reason’s 12 Principles of Error Management Back to the Future: Error Management AC-130J Prototype Written-Off After Flight Test LOC-I Overstress C-130 Fireball Due to Modification Error USAF RC-135V Rivet Joint Oxygen Fire: A military accident investigation has paradoxically determined that a $62.4mn fire was due to a maintenance error but that no human factors were involved. Inadequate Maintenance, An Engine Failure and Mishandling: Crash of a USAF WC-130H Inadequate Maintenance at a USAF Depot Featured in Fatal USMC KC-130T Accident USAF F-16C Crash at Joint Base Andrews: Engine Maintenance Error USAF Engine Shop in “Disarray” with a “Method of the Madness”: F-16CM Engine Fire MC-12W Loss of Control Orbiting Over Afghanistan: Lessons in Training and Urgent Operational Requirements UPDATE 30 March 2019: Contaminated Oxygen on ‘Air Force One’ Poor standards at a Boeing maintenance facility resulted in contamination of two oxygen systems on a USAF Presidential VC-25 (B747). UPDATE 30 October 2019: ‘Crazy’ KC-10 Boom Loss: Informal Maintenance Shift...

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S-76C+ MLG Collapsed Due to Pothole

Posted by on 6:31 pm in Accidents & Incidents, Airfields / Heliports / Helidecks, Helicopters, Offshore, Oil & Gas / IOGP / Energy, Safety Management

S-76C+ MLG Collapsed Due to Pothole On the 18 February 2018 Bristow US Sikorsky S-76C+ N860AL suffered a landing gear collapse during taxy at Acadiana Regional Airport (ARA), New Iberia, LA.  The aircraft was performing an offshore oil and gas flight for Talos Energy with 2 crew and 3 passengers. The Accident In their safety investigation report, the US National Transportation Safety Board (NTSB) say: The pilot reported that, while the copilot was taxiing the wheel-equipped helicopter to the runway for departure, he saw a “bump” on the concrete. The copilot reported that he attempted to stop before the “bump,” which turned out to be a pothole, but the helicopter struck the pothole with the right main landing gear, which collapsed. The pilot and the copilot both reported that the taxi speed was less than 5 knots. All 5 persons on board escaped uninjured.  The NTSB say that: The helicopter sustained substantial damage to the internal fuselage structure. The operator’s accident report form describes that this was a “non-maintained but commonly used taxiway/ramp” that was “made up of concrete sections that are approximately 12′ x 12′.” The NTSB documentation does not discuss why the surface was not previously identified as damaged and there is no follow up with the airport authority.  It is relatively unusual for an S-76 to operate from ARA so its just possible it was ground taxing along a route in which skidded helicopters would normally hover taxi and so the degraded paving was not normally an issue.  No safety actions are reported. Probable Cause The NTSB determined the probable cause to be: The helicopter’s striking of a pothole while taxiing, which resulted in the right main landing gear collapsing. Taxonomies of Flight Safety The NTSB classified this occurrence as an accident as per the following US legal definitions: 830.2 Definitions. As used in this part the following words or phrases are defined as follows: Aircraft accident means an occurrence associated with the operation of an aircraft which takes place between the time any person boards the aircraft with the intention of flight and all such persons have disembarked, and in which any person suffers death or serious injury, or in which the aircraft receives substantial damage. For purposes of this part, the definition of ‘‘aircraft accident’’ includes ‘‘unmanned aircraft accident,’’ as defined herein. Substantial damage means damage or failure which adversely affects the structural strength, performance, or flight characteristics of the aircraft, and which would normally require major repair or replacement of the affected component. Engine failure or damage limited to an engine if only one engine fails or is damaged, bent fairings or cowling, dented skin, small punctured holes in the skin or fabric, ground damage to rotor or propeller blades, and damage to landing gear, wheels, tires, flaps, engine accessories, brakes, or wingtips are not considered ‘‘substantial damage’’ for the purpose of this part. However, in the Bristow annual report for FY2018 (which ended 31 March 2018) the CEO oddly stated that the company “finished FY18 with no Class A or B air accidents” (implying no accidents with >$500k of damage).  This is an adaption of a US military designation system, not usually used in civil industry. UPDATE 28 February 2019: This was the only GOM accident in 2018: Helicopter Ops and Safety – Gulf of Mexico 2018 Update UPDATE 2 March 2019: The US military are discussing...

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Merlin Night Airprox: Systemic Issues

Posted by on 3:34 pm in Accidents & Incidents, Air Traffic Management / Airspace, Design & Certification, Helicopters, Human Factors / Performance, Military / Defence, Safety Management, Special Mission Aircraft

Merlin Night Airprox: Systemic Issues A Royal Navy Leonardo Merlin helicopter from RNAS Culdrose was in the hover, at night on 7 August 2018, slightly to the west of Falmouth at 40ft, facing west, with all floodlights on. The crew were conducting SAR training with a ‘dead-Fred’ training aid.  According to a report from the UK Airprox Board: At around 2217hrs, the final lift was being conducted and, as the training aid was being brought to the door, the ‘double-lift man’ and winch operator lost control of it and it fell back into the water. At this time, they heard another Merlin call that it was inbound on the Falmouth one-way route, that they were visual with [their] Merlin and would be passing over and crossing in front of the aircraft en-route to the Helford river. This was acknowledged… A short while later, the training aid had been recovered and the crew prepared to [return to base]. The Observer at the mission booth was tasked with contacting ATC for a clearance on the one-way route. At the same time, the LHS pilot conducted post-hoist-operation challenge and response checks, and the RHS pilot transitioned away from the hover, climbing to 1300ft QNH (approximately 1000ft QFE). As the aircraft levelled off, the [Traffic Advisory System] TAS declared ‘traffic 10 o’clock, 0 miles’. On looking in the 10 o’clock an aircraft was seen level at approximately 4nm but converging. At this point the aircraft commander liaised with the Observer and it was made clear that they did not have clearance on the Falmouth oneway route. A right-hand turn was initiated and, after turning through 30°, [the other] Merlin was seen at the same height crossing right-to-left about 4 rotor spans away (80m). The handling pilot instigated an avoiding action turn to the right, rolling out facing east, and an Airprox was declared to ATC. They continued out to sea until a clearance for the one-way route was obtained. This was categorised as a Cat A aiprox (“serious risk of collision“) with separation of just 39ft V / 80m H. The UKAB note that: The Merlin pilots shared an equal responsibility for collision avoidance and not to operate in such proximity to other aircraft as to create a collision hazard . If the incident geometry is considered as converging then Merlin(A) pilot [the one that had been hovering] was required to give way to Merlin(B). A safety investigation was conducted: Although both crews had received TAS warnings, the pilots assumed the TAS had ‘self-detected’ which had been a common fault when the TAS was first installed, but was no longer a fleet wide issue. Despite a well integrated glass coskpit… ..the TAS display unit was located on the lateral consoles in the cockpit (under the window, by the pilot’s elbow) making it difficult to view, and therefore the crews were reliant on the aural warning, which could easily be lost in the busy cockpit environment. This suggests TAS was a bolt on after thought. The [investigation reported that] crews [were] provided with detailed information on how the TAS works, but not what to do once it had alerted.  Furthermore, there was no policy within the Merlin fleet about how to respond to a TAS alert, and the crews did not double-press the TI selector for an aural update which would have given...

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AS350B2 Accident After Vibration from Unrecorded Maintenance

Posted by on 5:26 pm in Accidents & Incidents, Airfields / Heliports / Helidecks, Helicopters, Human Factors / Performance, Maintenance / Continuing Airworthiness / CAMOs, Safety Management

AS350B2 Accident After Vibration from Unrecorded Maintenance On 15 February 2018, Sahtu Helicopters (a subsidiary of Great Slave Helicopters) Airbus Helicopters AS350B2 C-FWCR landed on a 16 feet by 16 feet (i.e 0.27 D) helipad at a telecommunications tower at Bear Rock, Northwest Territories (NWT), and was shut down at 0958. The landing site is 3 nm WNW of Tulita (NWT), where the recorded temperature was −27 °C. According to the Transportation Safety Board (TSB) safety investigation report: Approximately 30 minutes after landing, given the temperature at the time, the pilot conducted a first engine run as per the AS350B2 flight manual supplement Instructions for Operation in Cold Weather, because pre-heat was not available. On start-up, the pilot felt vibrations consistent with those felt over the previous 3 days, both on the ground and during flight [see below]. At 1108, the pilot initiated the engine-start sequence for another engine run. The engine started and accelerated normally to 70% gas generator speed (Ng). The pilot increased the fuel flow control to the flight position. As the throttle was increased, the helicopter began bucking fore and aft on the landing gear skids. In response, the pilot decreased the fuel flow control, which increased the bucking. The pilot then decided to lift off in order to stop what he perceived to be ground resonance. The investigators note that: “Ground resonance does not normally occur in rigid or semi-rigid rotor systems because there is no drag hinge.  The AS350’s Starflex rotor system does not use lead-lag dampers The fuel flow control was quickly increased and the collective raised; however, the fuel flow control was not fully advanced and locked into the flight gate. Neither the main rotor rpm nor the engine rpm accelerated to the flight-governing range before the helicopter became airborne. The helicopter lifted several feet off the helipad, rotated to the left, and drifted approximately 30 m to the southeast. Given that the engine rpm had not accelerated into the flight-governing range, the rotor rpm subsequently drooped and the pilot was unable to maintain control of the helicopter. …the helicopter descended, collided with terrain and came to rest 50 m downslope of the helipad. The pilot was wearing the 4-point lap and shoulder harness, but was not wearing a helmet. He received serious injuries, but managed to egress the helicopter, return to the telecommunications tower service building, and contact the company to report the accident. The passenger who had been transported to the telecommunications tower administered first aid to the pilot. A company helicopter was dispatched from Fort Simpson, Northwest Territories, and arrived at approximately 1500 to transport the pilot to medical facilities in Yellowknife, Northwest Territories. The investigators reveal that: On 11 February 2018, 4 days before the accident, the helicopter was placed in the Great Slave Helicopter hangar overnight. An aircraft maintenance engineer had removed the main rotor blades with the assistance of the occurrence pilot and placed them on a wheeled storage rack, which was positioned beneath the helicopter tail boom after the helicopter was placed in the hangar. The TSB however don’t report why this was done. After reinstalling the main rotor blades on the morning of 12 February 2018, the occurrence pilot conducted an engine run, during which vibrations were noted. The vibration levels were not verified using vibration analysis equipment, which was available at the maintenance hangar. The...

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ADA AW139 A6-AWN Ditching off UAE, 29 April 2017: Final Report

Posted by on 3:46 pm in Accidents & Incidents, Helicopters, Human Factors / Performance, HUMS / VHM / UMS / IVHM, Maintenance / Continuing Airworthiness / CAMOs, Offshore, Oil & Gas / IOGP / Energy, Safety Management, Survivability / Ditching

ADA AW139 A6-AWN Ditching off UAE, 29 April 2017: Final Report Leonardo AW139 A6-AWN, operated by Abu Dhabi Aviation (ADA), made a precautionary ditching off the coast of the UAE near Mubarraz Island on 29 April 2017. The aircraft (MSN41213, a long-nose 139 built in the US in 2009) capsized before salvage.  This occurrence was subject to investigation by the Air Accident Investigation Sector (AAIS) of the UAE General Civil Aviation Authority (GCAA).  Their final report was issued in January 2019. History of the Flight The investigators report that the helicopter… ….departed Abu Dhabi International Airport, with two flight crew members and five passengers, for Dhabi II oil rig, located 33 nautical miles (nm) off the coast of Abu Dhabi in the Arabian Gulf. Four passengers disembarked after arrival at Dhabi II at 1231 LT, and the Aircraft continued towards oil rig BUNDUQ, approximately 78 nm further north-west. One minute into the climb after departing from Dhabi II, the flight crew received a high oil temperature warning for the main rotor gearbox (MGB) at approximately 490 feet (ft). The observed oil temperature was 109°C, when the Commander discontinued the climb and selected to descend to 500 ft. This action was taken to reduce power and the load on the MGB and was advised in the quick reference handbook (QRH). The flight crew decided to divert to the closest heliport, on Mubarraz Island, 18 nm from Dhabi II. Because the oil temperature continued to increase, the Commander decided to descend to 200 ft in preparation for a possible ditching. While descending through 210 ft, and with an oil temperature of 119°C, the flight crew heard a loud grinding noise emanating from the gearbox area. The Commander…decided to ditch the Aircraft. The crew activated the [AeroSekur] aircraft flotation system prior to touchdown, and the inflated bags kept the Aircraft afloat during the evacuation of all occupants into the life raft, from where they were rescued by the coast guard. As the left aft float slowly deflated, the Aircraft started to tilt and capsize. Emergency Flotation System The Operator provided annual practical safety and emergency procedure (SEP) training [which] featured warnings that flotation bags should not be deployed in-flight. The Rotorcraft Flight Manual contained the following warning: The failed aft left flotation bag displayed a tear in the vicinity of the composite cover remains, and delamination of seams near the pillow inflation valve and of the main chamber. The tear was most likely caused by the in-flight activation of the flotation system, when the float cover fragmented due to the inflation of the flotation bag.  An inspection of the Aircraft identified that the shear-bolts (attaching the upper edge of the float covers) had not sheared causing fracture of the composite covers leaving the remains attached to the Aircraft. The Aircraft manufacturer advised that this type of failure was evident during the certification process when the floats are deployed in-flight, resulting in a downward deployment instead of a sideway deployment of the flotation bags. The seam delamination on the flotation bag was probably caused by the rapid inflation of the flotation bag to operational pressure. This is supported by the Operator’s flotation bag reliability data, which indicated that a high number of flotation bags had failed the annual inflation test because of multiple defects, including seam delamination. This issue was known...

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Meeting Your Waterloo: Competence Assessment and Remembering the Lessons of Past Accidents

Posted by on 11:10 am in Accidents & Incidents, Human Factors / Performance, Maintenance / Continuing Airworthiness / CAMOs, Safety Culture, Safety Management

Meeting Your Waterloo: Collision at London Waterloo, 15 August 2017 Raises Questions of Competence Assessment and Remembering the Lessons of Past Accidents On the morning of 15 August 2017, a 10 coach South West Trains (SWT) passenger train, callsign 2D03, collided with a stationary engineering train at 13 mph while leaving Platform 11 at London Waterloo station. The Rail Accident Investigation Branch (RAIB) report that there were no injuries “but both trains were damaged and there was serious disruption to train services until the middle of the following day”. The SWT train was diverted from its intended route by a set of incorrectly positioned points (points 1524) and impacted the stationary engineering train, parked as a safety barrier to protect adjacent track works. https://youtu.be/TADSY0f0EHY At the time of the accident, platforms 1 to 10 were closed as part of capacity improvement works. https://youtu.be/hhQqKqpESYA Construction work was being undertaken in phases and had “required testing of signalling and points in the area of the accident near the end of platform 11”. The misaligned points were the result of a latent defect due to  “uncontrolled wiring [in blue below] added to the signalling system”. Design Precursors: Insufficient Management of Change and a Lack of a Shared Understanding The RAIB explain that: This wiring was added to overcome a problem that was encountered while testing signalling system modifications… The problem arose because the test equipment design process had not allowed for alterations being made to the signalling system after the test equipment [known as a test desk] was designed.  As a consequence, the uncontrolled wiring was added without the safeguards required by Network Rail signalling works testing standards, and remained in place when the line was returned to service. The RAIB describe how the design of the test desk had not kept pace with changes in the interlocking design (“signalling interlocking is a system of controls fitted to railway signalling equipment which prevents conflicting or unsafe routes from being set”).  The interlocking and the test deck were being designed by different companies.   A Network Rail’s signalling project engineer had queried how changes would be coordinated but the Mott McDonald Limited (MML) contractor’s responsible engineer (CRE) reassured him in error that OSL Rail‘s tester in charge (TIC) was taking care of this. There was also a crucial misunderstanding on when the test desk was connected.  In fact it was to still be connected for a period when the signalling was operational.  It should therefore have been treated as temporary works and subject to more stringent controls and a risk assessment conducted.  OSL’s TIC and the Network Rail project engineer understood it would remain connected but MML’s CRE did not and so the extra controls and risk assessment were not implemented.  The OSL ‘functional tester’ was also not aware that the test deck would remained connected when the signals were operational.  Furthermore: A project decision to secure the points in the correct position had not been implemented.  [While not carried out for these points] this [decision] was beyond normal requirements and the RAIB regards it as a good example of assessing site specific risks and identifying practical mitigation. Questions of Competence The RAIB go on to note the actions of the functional tester who they concluded had installed the extra wiring “were inconsistent with the competence expected of testers”.  They discuss the qualifications and work history of the functional...

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Japanese Rescue B412 Fatal CFIT

Posted by on 5:31 am in Accidents & Incidents, Crises / Emergency Response / SAR, Helicopters, Human Factors / Performance, Safety Management, Special Mission Aircraft

Japanese Rescue Bell 412EP Fatal CFIT On 5 March 2017 Bell 412EP JA97NA of the Nagano Fire and Disaster Prevention Aviation Center took off from Matsumoto Airport to conduct rescue training.  Visibility was good and the helicopters was flown single pilot, with a mechanic / hoist operator in the left hand seat and 7 rescue personnel in the cabin.  At around 13:41 local time, it was destroyed when it collided with trees and crashed onto the slopes of Mt. Hachibuse, Matsumoto City, Nagano Prefecture. All on board were fatally injured. The Safety Investigation The investigators of the Japan Transport Safety Board (JTSB) had the benefit of footage from a helmet camera worn by one of the rescue team.  However, the aircraft had neither a Flight Data Recorder (FDR) nor a Cockpit Voice Recorder (CVR). In their investigation report the JTSB explain the the helicopter’s route was estimated as follows: They say: After taking off from the Airport, the helicopter climbed at a speed of approximately 80 kt while heading northeast from the area above the city to over the mountains located about 9 km northeast of the Airport. The helicopter leveled off at about 1,740 m (5,700 ft)… It is somewhat likely that this was because the helicopter was trying to ensure the safety altitude of 150 m or higher from the destination, the Helipad, with an elevation of about 1,580 m. [It] then turned right over the mountains and headed toward Mt. Hachibuse, continuing roughly level flight at a speed of about 100 kt and at an altitude of about 1,740 m.  It is probable that the helicopter should have gone directly to the Helipad after turning right… …it is probable that this circuitous route was taken in order to make time to conduct engine data checks en route. The mechanic was mostly likely occupied with recording engine data.  The pilot’s right arm was observed to move briefly in the recorded video.  The investigators confirmed that the pilot had taken photos during the flight, something he had been warned against previously. The higher the mountains’ elevation got, the lower the helicopter’s altitude above ground level (AGL) became, despite the tree-covered mountainside that was looming ahead… Subsequently: …the helicopter collided with trees while maintaining attitude and speed. Branches and leaves scattered throughout the interior and about four seconds later, recording the video images stopped. The crash site was an approximately 40-degree north-facing slope covered with snow at an elevation of approximately 1,700 m, approximately 700 m north-northeast from the summit of Mt. Hachibuse (elevation: 1,928.8 m). The helicopter was turned upside-down with the nose pointing southwest. Much of the cabin was damaged by the force of impact from the front and above. Most of the aft fuselage was severely damaged with the engine attached to the engine deck. The Emergency Locator Transmitter (ELT) did not activate. Autopsy conclusions were that: The [56 year old] captain died from cardiac and aortic injury and the cause of death for the mechanic and seven rescuers were multiple trauma, all of which were caused by extremely strong blunt blows on the whole body. The pilot had a past medical history, discussed in detail by the JTSB, that they concluded should have been declared. Intriguingly they do not directly link the pilot’s recorded cause of death with pre-impact pilot incapacitation.  However, the...

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A319 / Cougar Airprox at MRS: ATC Busy, Failed Transponder and Helicopter Filtered From Radar

Posted by on 4:30 pm in Accidents & Incidents, Air Traffic Management / Airspace, Airfields / Heliports / Helidecks, Fixed Wing, Helicopters, Human Factors / Performance, Safety Management

A319 / Cougar Airprox at MRS: ATC Busy, Failed Transponder and Helicopter Filtered From Radar On 27 June 2016, Air France Airbus A319 F-GRHX, with 132 people onboard, passed Airbus Helicopters Cougar F-ZWBS with a minimum separation of 0.2 nm horizontally and 240 ft vertically on approach to Marseille-Provence Airport (close to the points marked ’10’ below). According to the Bureau d’Enquêtes et d’Analyses (BEA) investigation report (published only in French), the helicopter was returning from a VFR test flight to the east of the airport.  Its transponder had failed in flight so air traffic control only had primary radar contact. The BEA comment this hazard may have been underestimated and there was excessive confidence in the primary radar’s tracking. The helicopter crew were told they would land behind a Lufthansa A320 on Runway 31R by the Tower Controller.  They were shortly after told to land on 32L instead. The Air France, operated for Hop!, was performing a visual approach to Runway 31R and were also told they were number 2 behind the A320 by the Approach Controller.  They were unaware of the presence of the helicopter.  The Tower frequency was noted to be busy (it was active for about 80% of the time, which is very high use say the BEA). The investigators note that use of non-standard phraseology in French contributed significantly to the congestion of the tower frequency. While on base leg, the Cougar crew slowed significantly and came into the hover at point 3.  The primary radar then automatically filtered out the slow moving target (the cyan track below), even when the speed increased. The Cougar crew were meanwhile visually searching for a Robin DR400 light aircraft that was to the west.  As they crossed the approach to 31R to intersect 31L they were unaware that the A319 was behind them and closing.  It as at this point the minimum separation occurred. The A319’s TCAS could not detect the helicopter because of the faulty helicopter transponder.  Visual acquisition was difficult as the helicopter, intended for a military customer, was camouflaged and being viewed against the ground.  The BEA comment that the closing speed “also makes it difficult to apply the concept of ‘see and to avoid”.  The BEA comment that the helicopter crew, being Marseilles based, has been able to develop mutual trust with the local controllers. So, as the crews are familiar with the terrain, there was less rigour in position reports and the controllers may haven been less vigilant in tracking them. While this might be adequate normally, it could aggravate unexpected event. Other MAC Safety Resources Aerossurance has previously published: Military Mid Air Collisions Military Airprox in Sweden North Sea S-92A Helicopter Airprox Feb 2017 Mid Air Collision Typhoon & Learjet 35 USMC CH-53E Readiness Crisis and Mid Air Collision Catastrophe Avoiding Mid Air Collisions: 5 Seconds to Impact AAIB Highlight Electronic Conspicuity and the Limitations of See and Avoid after Mid Air Collision Fatal Biplane/Helicopter Mid Air Collision in Spain, 30 December 2017 UPDATE 16 February 2019: Merlin Night Airprox: Systemic Issues UPDATE 12 May 2019: Alaskan Mid Air Collision at Non-Tower Controlled Airfield UPDATE 14 August 2021: Alpine MAC ANSV Report: Ascending AS350B3 and Descending Jodel D.140E Collided Over Glacier UPDATE 18 June 2022: Limitations of See and Avoid: Four Die in HEMS Helicopter / PA-28 Mid Air Collision Aerossurance has extensive air safety, operations, airworthiness, human factors, aviation regulation and safety analysis experience.  For practical aviation advice you can trust, contact us at:...

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Production Defect IFSD Triggers Night Deadstick PC-12 Landing

Posted by on 7:53 am in Accidents & Incidents, Fixed Wing, Safety Management, Special Mission Aircraft

Production Defect IFSD Triggers Night Deadstick PC-12 Landing On 29 January 2010, a Pilatus PC-12/45 VH-NWO, was being operated by the Royal Flying Doctor Service (RFDS) on a night medical evacuation flight from Derby to Kununurra, Western Australia. As the aircraft was passing through 18,000 ft, the Pratt & Whitney Canada (PWC) PT6A-67B engine exhibited a number of problems, so the pilot turned the aircraft back to Derby. WA. The engine subsequently failed approximately 6 nm from Derby and the pilot glided the aircraft to a safe deadstick landing. There were no injuries to the 4 persons on board. According to the Australian Transport Safety Bureau (ATSB) safety investigation report, subsequent examination confirmed that the engine propeller reduction gearbox had seized. …four of the six first stage reduction assembly carrier bolts (part number MS 9490-34) had failed due to fatigue cracking at the head-to-shank fillet radius. Debris from the failed bolts was released into the first stage sun and planet gears, causing significant damage. A fifth carrier bolt had fractured through the threaded area as a result of overstress, with the threaded portion remaining in the splined adapter.  [ATSB] examination confirmed the mode of failure as reverse bending fatigue below the head of four of the bolts. In October 2010, the engine manufacturer advised the ATSB of the identification of a number of in-service carrier bolts that had not been cold rolled at the head-to-shank fillet radius. That would have reduced the bolts’ fatigue resistance, and increased the likelihood for the initiation of fatigue cracking at the head-to-shank fillet radius. It was reported that the bolt manufacturer only cold rolled the head-to-shank fillet radius when it was considered necessary to remove evidence of grinding or tool marks on bolts during the manufacturing process. SAE Aerospace Standard (AS) 7477 Revision D in fact ambiguously stated: The head-to-shank fillet radius…shall be cold worked sufficiently to remove all visual evidence of grinding or tool marks. This has been intended to require the head-to-shank fillet radius be cold rolled in all cases. A revised copy of the specification, Revision E, was published by the SAE in October 2011, clarifying the need for cold rolling of the head-to-shank fillet radius of those bolts The discovery that many of the in-service bolts had not been cold rolled meant that those bolts had lower strength and fatigue resistance than was necessarily the case. The investigation found that, between 2000 and the incident involving VH-NWO in January 2010, there were a total of 27 failures of the larger variants of the PT6A series engines due to failure of the first stage carrier bolts at the head-to-shank fillet radius. During that period, there were 2,029 of these engines in service worldwide. As a result, the engine manufacturer issued a number of service bulletins that identified affected gearboxes and provided recommended compliance times for the removal of suspect carrier bolts from service. Safety Resources You may also find these Aerossurance articles of interest: Embraer ERJ-190 EWIS Production Quality a Factor in Fire S-92A Flying Control Restriction on Wiring Loom ERJ175 NLG Uplock Spring Production Defect Eclipse 500 Landing Gear Production Defect Production Errors on a SAR Helicopter Full Ice Protection System Production Defect IFSD Triggers Night Deadstick PC-12 Landing Machining Defect Cause of V2500 Failure RCAF Investigate Defect on Newly Delivered CH-148 Cyclone (S-92) PA-34 Electrical Short Melted Rudder Cable UPDATE 17...

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