Fatal Engine Power Loss: Powerline Helicopter Not Modified IAW OEM Recommendations
Fatal Engine Power Loss: Powerline Helicopter Not Modified IAW OEM Recommendations We look at a fatal accident that demonstrates the criticality of assessing recommended service bulletins. On 4 May 2016 MD Helicopters MD369E / MD500E helicopter N629JK operated by Rotor Blade suffered an engine failure while approaching a 125ft high electricity pylon near Reedsville, WI to collect two linesmen using a 50ft long line. It impacted trees and terrain. The pilot was killed by blunt force trauma to the chest and head despite wearing an MSA LH250 helmet. Safety Investigation The US National Transportation Safety Board (NTSB) report that the main shaft of the Rolls-Royce M250-C20B engine’s Honeywell power turbine governor (PTG) was found fractured. The NTSB found that a: …portion of the fractured drive shaft remained embedded in the spindle of the spool bearing assembly. The fracture surface features of the shaft were consistent with overstress. The outer cap of the spool bearing assembly was removed, and the ball bearings and spacers were found coated with voluminous, powdery, black particulate. Much of the powder fell from the assembly upon removal of the cap. No grease was observed. Disassembly of the bearings revealed that the ball retainers were fragmented, the inner surfaces were found coated with a powdery, black particulate, and no grease was observed. The inner bearing surfaces were rough and frosted. Component History Honeywell introduced this type of dual-spool bearing in 2003 “to lower cost of ownership and commonize the design”, replacing an earlier single-spool bearing. While the original design had no previous service issues, the NTSB report that the dual-spool bearing “had experienced a total of 23 failures before this accident”. These resulted in either engine oscillations, uncommanded engine acceleration or, as in this case, a loss of engine power. Due to this adverse service experience the NTSB say that: Honeywell issued SB [Service Bulletin] GT-73-344, Revision 2, on October 30, 2008, to replace the bearing assembly on PTGs used on Rolls-Royce 250 series engines in order to increase PTG reliability. The SB applied to several PTG models including the AL-AA2 model on the accident engine. Revision 1 was issued March 7, 2008. The Engine Type Certificate Holder (TCH), Rolls-Royce, issued Commercial Engine Bulletin (CEB) 1402 on 21 April 2008 that referenced Honeywell SB GT-73-344 and specified compliance times. The Federal Aviation Administration (FAA) did not however elect to make this mandatory with an Airworthiness Directive. Rotor Blades’ Continuing Airworthiness Management At the time of the accident, the engine, built in 2007 (while the dual-spool bearing was still being fitted), had accumulated 1,048.7 hours Time Since New (TSN). On 3 April 3, 2016, at 987.4 hours engine TT, a 150-hour engine inspection was completed along with a series of repairs. The TCH’s April 2008 recommendation was for this spool to have be changed by 750 hours TSN. Despite operating at low altitude missions in a single engined helicopter Rotor Blade had not followed the recommendation and the PTG remained fitted with the dual-spool bearing with the known adverse service experience. Disappointingly the NTSB record no information on how Rotor Blade assessed recommended service bulletins and other safety information and do not discuss what risk assessments, if any, the operator had conducted. NTSB Probable Cause The failure of the power turbine governor’s dual-spool bearing due to a lack of lubrication, which resulted in a complete loss of engine power and subsequent impact with terrain....
read moreHeli-Expo 2018 Photo Report
Heli-Expo 2018 Photo Report Its that time again! We bring news from the annual HAI Heli-Expo being held this year, as the sign says, in ‘fabulous Las Vegas, Nevada’. All show photos © Aerossurance unless otherwise stated. Airbus Helicopters H160 Airbus brought the second prototype H160 to the US for Heli-Expo, a sales tour and high altitude testing in Colorado. Production H160 central and front fuselages will be produced pre-equipped at Donauworth in Germany. Tail booms produced Albacete in Spain, and main rotor blades would be produced at La Courneuve, near Paris. They will be assembled in Marignane near Marseilles, where the dynamic components are also produced. Airbus is introducing new lean production processes aiming to reduce assembly to just 24 weeks, compared with 36 for the AS365N3. Of special note was the effort Airbus went to to demonstrate that the SafranArrano powered H160 has also been designed for maintainability. All scheduled maintenance (with the exception of the 50 hour oil check and top up) is visual only. Twice each day Airbus staged a demonstration of access to the upper deck. Note the fall arrest system, attached by a yellow strop around a blade spindle (a technique pioneered for the original Bristow AS332L2 JIGSAW SAR trial with G-JSAR). All hydraulics is above the cabin in the production aircraft, as the landing gear will be electrically actuated. This prototype did feature a stand-alone hydraulic pack in the baggage bay. At the show Babcock announced a five year frame agreement for the purchase of a fleet of H160s as launch customer. Bell 525 Bristow signed a Memorandum of Understanding (MoU) with the rebranded Bell to explore the 525’s possible use in the search and rescue (SAR) role. Certification of the 525 is expected “early 2019” after a delay caused by an accident in flight test (see: Bell 525 Prototype N525TA Fatal Flight Test Accident). One relatively unique feature of the 525 is Fly By Wire (FBW) controls. Bell 212 This refurbished Era B212 was on show. Leonardo AW139 MUH Leasing company Waypoint has commissioned the conversion of an early short nose Leonardo AW139 to a Medium Utility Helicopter (MUH) configuration with the aim of placing redundant oil and gas helicopters into the onshore utility sector. Leonardo AW169 In our opinion the smartest colour scheme at the show was this AW169. Leonardo AW609 Era are to take delivery of two AW609 tilt rotors in 2020, making them US launch customer. They could be used in a variety of missions, including offshore/utility, VIP transport, EMS and SAR (Era have not settled on a specific role). Like the B525, the AW609 suffered an accident in flight test that has delayed certification. Sikorsky S-70 Firehawk and Black Hawk An LA County Fire Sikorsky S-70 Firehawk was on show: Also on show was an S-70 Black Hawk of the US Customs and Border Protection (CBP) Air and Marine Operations (AMO), a component of the Department of Homeland Security (DHS). AMO use the type to perform missions such as “maritime, aviation, and land interdiction; insertion of agents in remote areas; and joint operations during contingency operations and national taskings, such as disaster response”. In most cases the this message on the tail feels more like a warning to their targets than those unaware of the danger of the tail rotor! UPDATE 25 March 2018: Black Hawks for hire Human Centred Design An excellent initiative to create more Human Centred Design by use of a Human...
read moreSwedish Military NOE Helicopter Bird Strike
Swedish Military NOE Helicopter Bird Strike During a night training flight using Night Vision Goggles (NVG), one of a pair of Swedish Armed Forces Agusta 109LUHs (known to the Swedish military as a Helicopter 15), 152-765, collided with a bird on 3 February 2017. The bird went through the windshield and struck the student pilot resulting in serious facial injuries. The instructor was able to take control and perform a safe landing. The Accident Flight The Swedish Accident Investigation Authority (SHK) has issued their report (in Swedish but with an English summary). The training exercise near Sveg in Northern Sweden, involved Nap of the Earth (NOE) flight as low as 20ft. The area had been used for exercises for 7 years, with ‘Recognized Exercise Paths’ established. The aircraft was at around 35ft and 100 knots when it hit a Western Capercaillie (otherwise known as a Wood Grouse) with an estimated weight between 3.6 and 4.8 kg. There are about 700,000 of these in Sweden, with a greater propensity in the north of the country. They most active during dawn and dusk but do take to the air at night when scared. The bird went through the right hand windshield. The student’s helmet was split, their NVGs knocked off and the student’s spectacles broken. The right hand pilot’s door upper and lower locks were also damaged. The instructor landed at a site where the second helicopter could recovery the injured pilot. The investigators believe the pilot’s spectacles may have provided some extra protection form the bird debris and NVGs. A risk analysis had been carried out before the exercise using an Operational Risk Management Method (ORM) tool, with 17 different hazards identified. Although bird strike was considered the only mitigations were post-impact recovery measures. Similarly SAR helicopter cover was a mitigation to a number of accident scenarios but there was minimal change to the exercise when it was known the cloud base was too low for Swedish Maritime Administration Leonardo AW139 SAR cover. The investigators do accept that: [The probability of] collision with such large birds may generally be considered to be low. However, there are several parameters that affect the probability, such as the area of the flight, the time, the flight altitude and the speed. Certification Requirements The A109 was certified according to JAR-27. This required the windscreen resist aerodynamic forces that occur during flight up to maximum speed with a sufficient safety margin and it does not fragment into small debris when damaged. There is no specific requirement on bird strike resistance even in current EASA CS-27 / FAA FAR-27. The operating unit were not aware of this. Part 29, for civil rotorcraft over 3,175 kg does now have a 1 kg bird strike requirement at maximum speed up to 8,000ft. The NH90 (Helicopter 14) can withstand a collision with a bird weighing 1 kg up to 300 km/h. The Sikorsky UH-60M Black Hawk (Helicopter 16) can withstand a 1.8 kg bird at the maximum speed up to c5,000ft report the SHK. SHK Safety Analysis and Conclusions The investigators say: It is clear from the investigation that the risk analysis performed before the training only took into account the risk of bird strike to a limited extent, and that there was a lack of knowledge regarding helicopter 15’s certification requirements with regard to bird strikes. The accident was a result of the exercise not being sufficiently adapted in terms of altitude and speed on account of the incidence of...
read moreNTSB Reveal Lax Maintenance Standards in Honolulu Tour Helicopter Accident
NTSB Reveal Lax Maintenance Standards in Honolulu Tour Helicopter Accident (Bell 206B3 N80918) On 18 February 2016 a Bell 206B3, N80918, operated by Genesis Helicopters, impacted the water of Pearl Harbour, Honolulu, HI during a scenic tour following a transmission component failure due to poor maintenance. One passenger, a 16 year old boy, died in hospital 4 days later, after this Survivable Water Impact (SWI). The pilot and two other passengers suffered serious injuries and a fourth passenger escaped with minor injuries. The US National Transportation Safety Board (NTSB) safety investigation highlights some shocking maintenance standards. The Accident Flight During the local scenic flight the pilot explained that: …as he began the approach to Ford Island [in the centre of Pearl Harbour], he noticed a vibration throughout the cabin of the helicopter that seemed “different.” He decided to return directly to HNL [Honolulu Airport]; however, the vibration stopped, and he made a left turn so the passengers could see the USS Arizona Memorial. Shortly thereafter, the vibration returned, and the pilot called the air traffic control tower at HNL to advise that the flight would be returning to the airport. The controller instructed the pilot to hold for other inbound helicopters, which implies no emergency was declared at that time. …at this point, the vibration developed into a grinding sensation. Then the main rotor low rpm warning light illuminated, and engine rpm began to rise; the point where the engine and rotor RPM needles were no longer matched on the power turbine gauge. The pilot then lowered the collective, reduced the throttle and realized the engine and main rotor were no longer connected as he began to look for a place to land. His first chosen landing site, the grassy area next to Pearl Harbor Memorial visitor’s centre, became impossible as the USS Arizona Memorial ferry had started to disembark there. …the pilot turned the helicopter slightly left to land [i.e. ditch] in the water as close to shore as possible… He stated that when the helicopter was about 20 ft above the water, it felt like the rotor stalled, the helicopter lost lift, and it “fell out of the sky.” The helicopter descended rapidly into the water about 20 ft from the shoreline. A review of video captured by a witness revealed that the…helicopter’s forward airspeed appeared to decrease, the nose pitched up, and the helicopter began to rotate to the left in a slightly nose-up attitude then descended rapidly into the water. At the time of impact, the helicopter appeared to be in a slightly nose-high, left bank attitude. The 16 year old boy was trapped in the helicopter. A number of ‘good samaritans’ near the memorial, including a police officer and a navy diver, made 5-6 attempts to free the boy from the submerging wreckage. When they did release him, he was taken to shore and treated by visiting medical personnel, although he died in hospital on 22 February 2016. The official cause of death was anoxic encephalopathy, or brain injury, due to drowning. Genesis Helicopters and their FAA Oversight Genesis Helicopters, founded in 1999, operated a single helicopter and employed 4 people: the owner (who was a licensed pilot and A&P mechanic) a mechanic’s assistant (who was unlicensed) a pilot (who was flying the helicopter that day) a receptionist They had a Letter of Authorization (LOA) from the Federal...
read moreFlawed Post-Flight and Pre-Flight Inspections Miss Propeller Damage
Flawed Post-Flight and Pre-Flight Inspections Miss Propeller Damage (Rex Saab 340 VH-ZRL) We look at an Australian Transport Safety Bureau (ATSB) report into a regional turbprop incident and in particular why propeller damage was missed on several inspections. The Incident Flight On the evening of 22 February 2013, Regional Express (Rex) Saab 340B VH-ZRL, was on approach to Taree, NSW. The crew were monitoring the weather. The crosswind was reported as 50 knots when they were at about 6,000 ft, although it decreased as the aircraft descended. At 700-800 ft above ground level (AGL), the crew became visual with the runway and committed to landing. At that point the wind was fluctuating and there was light rain. On touch down however the aircraft was subject to a gust, which made the left wing lift slightly and the aircraft to weathercock to the left, into wind. Reverse thrust had already been selected. As the aircraft veered toward the runway edge the Commander, who had been the Pilot Monitoring, took control of the aircraft. The ATSB say: He applied right rudder, but the aircraft did not respond. As the aircraft’s airspeed decreased, the captain also applied right brake, with no effect. He then simultaneously commenced nose wheel steering using the tiller. As the captain believed that the nose wheel steering was ineffective, he elected to apply asymmetric thrust by reducing the amount of reverse thrust on the left engine and increasing reverse thrust on the right engine. The aircraft commenced moving to the right. The crew were unable to determine how far left the aircraft had veered due to the water spray from the application of reverse thrust, but believed the aircraft had not departed the runway. The aircraft taxied to the parking area. As the passengers disembarked there were strong winds and heavy rain. Post Flight Actions Using a torch, the FO then conducted a post flight inspection, which included examining the left landing gear and propellers. At the same time, refuelling of the aircraft commenced and the captain was completing paperwork. After finishing the post-flight inspection, the FO advised the captain that nil damage was found. In preparation for the next flight to Grafton, the Captain commenced an external inspection of the aircraft using a torch…it was raining heavily. He examined the left landing gear and reported that no mud or grass was observed. As he continued toward the left propeller, he was interrupted by the refueller. The captain then went back into the cockpit with the refueller and was further distracted by the company’s ground handling agent. As a result, the captain did not get the opportunity to inspect the left propeller blades. The aircraft captain then conducted a runway inspection for contamination with the ground handling agent. There was “a substantial amount of standing water” and a 30 knot crosswind so the flight was cancelled. There was no evidence visible that the aircraft had earlier left the runway. The next day the flight to Grafton was conducted. The FO made the external inspections of the aircraft. The aircraft then returned to Sydney, at which time maintenance personnel conducted an inspection of the aircraft and observed damage to the left propeller blades. All four blades had sustained stone damage predominantly on the back (reverse) of the blades. Runway 04/22 at Taree consisted of a 30 m wide runway with...
read moreFatal Fall From B429 During Helicopter Hoist Training
Fatal Fall From B429 During Helicopter Hoist Training On 11 July 2016 Delaware State Police (DSP) Aviation Unit Bell 429 helicopter N1SP was performing recurrent rescue hoist training with volunteer fireman of the Delaware Air Rescue Team (DART) at Delaware Coastal Airport, Georgetown, DE when the hoist system operator (aka winch operator) fell from the helicopter and was fatally injured. The DSP were the first para-public B429 customer, taking delivery of two in 2014. NTSB Safety Investigation In their recently issued report, the US National Transportation Safety Board (NTSB) say there were three crew members in the cabin who: …needed to complete 3 evolutions in each position [rescue specialist, a system operator, and a safety officer] to complete the recurrent training. All three individuals had most recently completed hoist operation training on June 15, 2016. This was Class D Human External Cargo (HEC) training by Priority 1 Air Rescue. On the day of the accident: During an evolution, the rescue specialist would be lowered from the helicopter. The system operator, located on the helicopter’s skid, would retract the hook back into the helicopter, and the pilot would then return the helicopter to the original hover position in flight. Then, the rescue specialist would cue the crew to return to the target area (where the rescue specialist was located). The system operator would extend the hook, the rescue specialist would connect himself to the hoist, and the system operator would raise the rescue specialist back into the helicopter. After three evolutions, the pilot would land the helicopter; the crew would rotate positions and restart the process. According to a rescue checklist, the security of each member’s safety harness was checked before each takeoff. The system operator wore an Aerial Machine and Tool Corp H1037-BL/M full body harness rated to 2,900 pounds. It incorporated 4 tether points; 2 on the front of the harness and 2 on the back. Each tether point incorporated a D-ring that could attach to a carabiner connected to the interior of the helicopter. The accident flight was the seventh evolution of the day, and the first flight where the fatally-injured crewmember acted as the system operator. DSP procedures required two other people check the security of the restraints. The safety officer and rescue specialist reported they checked and verified that the restraints were secure. The helicopter then lifted off the ground, moved to the practice area, and the system operator requested and was granted permission by the pilot to move to the helicopter skid. The system operator stepped onto the skid [from where we would control the hoist and guide the hoist cable] and fell from the helicopter. The pilot stated that throughout the accident sequence, the crew was not rushing while they completed the checklists. Investigators say: Examination of the system operator’s equipment did not reveal any failures or malfunctions that would explain the fall. Additionally, examination of the tether to the helicopter did not reveal any abnormalities. In the absence of any equipment failure, it is likely that the system operator was not fastened to the helicopter. NTSB Probable Cause The emergency response team’s failure to ensure that the system operator was secured to the helicopter, which resulted in his fall during the recurrent rescue hoist training operation. Our Observation Even with recently trained personnel and two independent checks of the harness, the winch operator was unsecured when he stepped...
read moreLost in Translation: Misrigged Main Landing Gear
Lost in Translation: Misrigged Main Landing Gear The French BEA-D (Le Bureau Enquêtes Accidents Défense – Air (UPDATE: renamed the BEA d’État [BEA-É] in 2018 in recognition of its role in all state aircraft) has issued the final report into their investigation of a landing gear collapse on Canadair CL-415 F-ZBEU of the Securité Civile at Ajaccio-Napoleon Bonaparte Airport, Corsica on 1 August 2016. The Occurrence The fire bomber, callsign ‘Pélican 42’, was one of two aircraft taxying for take-off when the right hand Main Landing Gear (MLG) collapsed as the aircraft turned to align with runway 20 for take off. In particular the right hand float was damaged, and a fuel leak occurred. Safety Investigation The MLG is locked by a strut by the principle of a geometric locking by overextension. When examined the MLG strut was found to be outside the allowable range which led to premature wear of the components of the strut assembly. The recommended value for X in the Component Maintenance Manual (CMM): Dimension X must be equal to dimension Y or up to a maximum of 0.055 inch (1.40 mm) less than dimension Y. The investigation revealed that the maintenance organisation overhauling the landing gear struts had translated the CMM from English to French but had made an error with this dimension: The landing gear was jolted unlocked when the aircraft taxied onto the runway at a higher than intended speed (c 14 knots rather than 6 knots). Safety Resources Aerossurance has previously published: Aircraft Maintenance: Going for Gold? Professor James Reason’s 12 Principles of Error Management Critical Maintenance Tasks: EASA Part-M & -145 Change Airworthiness Matters: Next Generation Maintenance Human Factors B747 Landing Gear Failure Due to Omission of Rig Pin During Maintenance When Down Is Up: 747 Actuator Installation Incident Maintenance Human Factors in Finnish F406 Landing Gear Collapse Safety investigators discuss the associated maintenance human factors and inadequacies in the type’s maintenance instructions. UPDATE 24 June 2018: B1900D Emergency Landing: Maintenance Standards & Practices The TSB report posses many questions on the management and oversight of aircraft maintenance, competency and maintenance standards & practices. We look at opportunities for forward thinking MROs to improve their maintenance standards and practices. UPDATE 25 August 2018: Crossed Cables: Colgan Air B1900D N240CJ Maintenance Error On 26 August 2003 a B1900D crashed on take off after errors during flying control maintenance. We look at the maintenance human factor safety lessons from this and another B1900 accident that year. UPDATE 3 November 2018: A Lufthansa MD-11F Nose Wheel Detached after Maintenance Error UPDATE 28 April 2020: Beech 99A MLG Collapse UPDATE 3 June 2020: Beechcraft 1900C Landing Gear Collapse at San Antonio, TX UPDATE 16 June 2020: CRJ-200 Landing Incident Highlighted US Maintenance Competency Inadequacies UPDATE 23 June 2020: Myanmar National Embraer 190 NLG Jam: Maintenance Error? We’re Not Convinced! UPDATE 12 October 2020: Frozen Dash 8-100 Landing Gear After ‘Improper Maintenance Practices’ Say NTSB Aerossurance is pleased to sponsor the 9th European Society of Air Safety Investigators (ESASI) Regional Seminar in Riga, Latvia 23 and 24 May 2018. Aerossurance is pleased to be both sponsoring and presenting at a Royal Aeronautical Society (RAeS) Human Factors Group: Engineering seminar Maintenance Error: Are we learning? to be held on 9 May 2019 at Cranfield University. 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: enquiries@aerossurance.com Follow us on LinkedIn and on Twitter @Aerossurance for our latest...
read moreComplacency: A Useful Concept in Safety Investigations?
Complacency: A Useful Concept in Safety Investigations? There is a fine line between confidence (from the Latin confidentia ‘to have full trust’) and over-confidence. Daniel Kahneman contends that of all the various flaws that bedevil decision-making, over-confidence is the most damaging. While an etymologist may argue ‘complacency’ (from the Latin complacentia ‘to please’) is more about smugness, it is often used in a similar way to over-confidence. But is complacency just another convenient ‘label‘ for impatient investigators to apply? Is is not by its nature (unlike confidence) an unhelpfully negative concept? Moray & Inagaki (2000) say: To claim that behaviour is complacent is to blame the operator for failure to detect signals. This is undesirable, since so-called complacent behaviour may rather be the fault of poor systems design. Indeed is complacency only about signal detection? Is it just about front-line operators? We look at a paper that examined complacency, proposed a different way of framing the concept and how one accident investigation agency choose to recommend tackling it. A Theory of Complacency In a paper presented at the 2012 IChemE Hazards 23 conference Gemma Innes-Jones of LR Scandpower wrote: Complacency is one aspect of operator behaviour that is often cited as a major contributing factor to accidents… In everyday usage complacency is often used to suggest wilful and ill-advised neglect on the part of an individual. Some of the common symptoms suggested in accident reports include ignoring warning signs, over confidence, assuming the risk decreases over time, neglecting safety procedures, becoming satisfied with the status quo, the erosion of the desire to remain proficient and accepting lower standards of performance. Complacency has also been defined in relation to boredom, overreliance, overconfidence, contentment, a low index of suspicion, workload and resource allocation, trust in automation and attention [see paper for citations]. An earlier paradoxical definition was that (emphasis added): Complacency is caused by the very things that should prevent accidents, factors like experience, training and knowledge contribute to complacency. Complacency makes crews skip hurriedly through checklists, fail to monitor instruments closely or utilize all navigational aids. It can cause a crew to use shortcuts and poor judgement and to resort to other malpractices that mean the difference between hazardous performance and professional performance. Wiener, E.L. (1981). Complacency: is the term useful for air safety? 26th Corporate Aviation Safety Seminar, Flight Safety Foundation Examples: Kern highlights one example of what he calls ‘creeping complacency’ were an EMB-120 Brasilia pilot who was a ‘stand-out aviator’, flying a routine route, responded to a cabin crew request and doubled the rate of climb, causing a near fatal accident. The NTSB identified complacency in a police helicopter accident, where a demanding night flight was commenced and opportunities to land as conditions deteriorated were ignored. The NBAA mentioned complacency in a report that highlighted that FDM data showed a low compliance with pre-take off flight control checks amongst business aviation pilots. UK AAIB quote a pilot commenting on complacency in his miscalculation of A320 take off performance at his home base. A First Officer commented on the ease of becoming complacent during repetitive, frequent operations in an ATSB report. A Service Inquiry into the death of a soldier whilst sports parachuting commented on an organisationally “complacent approach to safety, training and parachute operations”. In some cases complacency is used as a term but not defined. For example, Gareth Lock has pointed out that the Human Factors Analysis and Classification System (HFACS) taxonomy “lists it as part of adverse mental states but don’t...
read moreWasp Stung By Lack of Lubrication
Wasp Stung By Lack of Lubrication An accident involving civil registered ex-military Westland Wasp HAS1 G-KAXT on 23 September 2016 highlights the importance of a thorough review of an aircraft’s maintenance programme when there is a major change in role or utilisation. The Aircraft G-KAXT was delivered to the Royal Navy in February 1967 with the UK military registration XT787. The helicopter was transferred to the Royal New Zealand Air Force (RNZAF) in 1982, where it remained in service until May 1998. It was acquired by a private owner in 2000 at approximately 2,660 flying hours and registered as G-KAXT. It had accumulated a total of 3,012 flying hours and was operating on the UK civil register with a valid Permit to Fly. The AAIB say: The helicopter was maintained in accordance with the Ministry of Defence (MoD) Master Maintenance Schedule (MMS), reference AP101C-0601-5A1; this was a condition of the CAA approval for the Permit to Fly. The scrap life of the main rotor gearbox is 2,400 hours and the overhaul periodicity depends on the equipment modification state. In the case of G-KAXT, the overhaul period was 600 hours. The manufacturer advised that typical usage for the Wasp helicopter in UK military service was in the order of 200 hours per year, which would equate to a gearbox overhaul calendar period of approximately three years. Accident Flight The AAIB explain that while en route from AAC Middle Wallop to RNAS Yeovilton on 23 September 2016: Southwest of Salisbury, at approximately 1,150 ft and 80 kt, the pilot felt a two to three second vibration in the collective lever. Shortly thereafter, the pilot realised that he no longer had collective pitch control, so he turned away from rising ground in preparation for a diversion to a landing site in the Chalke Valley. The pilot made a PAN call and informed Air Traffic Control (ATC) of his intention to land as soon as possible. He was offered diversionary airfields, but with increasing concern over the ability to control his altitude he decided to land in a field near the village of Bishopstone. After a slow speed handling check, he initiated his final approach and selected manual throttle control at a height of approximately 300 ft. His ability to flare was limited and he was unable to cushion the landing, with one wheel touching down first and significant bouncing between all four wheels as he shut the helicopter down. The tail rotor struck the ground but the helicopter remained upright and both occupants, who were uninjured, were able to exit normally. The Safety Investigation AAIB established that the collective pitch control rod in the main rotor gearbox had broken. The failure occurred in an area where the rod passes through an aperture in a metallic ‘guide’ (by design, the rod should not touch the guide say AAIB). However, this was secondary to a universal joint failure in the cyclic control circuit. That failure was due to lack of lubrication and a build-up of corrosion deposits. The corrosion deposits indicated that the failure was not recent. The exposed bearing surfaces of the trunnion showed extensive corrosion and wear. The evidence indicated that that the universal joint had been operating with insufficient lubrication for a considerable period of time. According to AP101C-0601-5A1, a new universal joint must be installed every 600 hours....
read moreDispatcher Forced to Run After Distracted Pushback
Dispatcher Forced to Run After Distracted Pushback A dispatcher was forced to run when an aircraft started to taxi while he was still connected to it. On 25 January 2017, a Jetstar Airbus A320-232, VH-VGJ was being prepared for pushback from bay 4 at Newcastle (Williamtown) Airport, NSW. The Australian Transport Safety Bureau (ATSB) report that: At about 1836, the crew received a clearance from the surface movement controller to pushback, which placed VGJ to the right rear quarter of an aircraft parked on bay 5. The aircraft dispatcher walked beside the aircraft and was connected to the nose of VGJ by a headset for communications with the flight crew. At about 1838, the crew of the aircraft on bay 5 requested a clearance to taxi for departure. At this stage, the crew on board VGJ interrupted their ‘after start flows’ to monitor the other aircraft, which they believed posed a collision risk. At about 1840, the crew on board VGJ requested and received a clearance to taxi for departure. The dispatcher for VGJ was still connected to the aircraft nose with their headset and waiting for their clearance from the flight crew to disconnect. They observed the taxi lights for VGJ illuminate, then they heard the engine noise increase, and then the aircraft started to taxi. …they immediately disconnected their headset from the aircraft and ran clear to the left of the aircraft towards the terminal… Once the dispatcher was clear of the aircraft, they turned around to display the nose wheel steering pin to the flight crew, but the captain was not looking towards them. Flight Crew Procedures After starting both engines, the crew conduct ‘after start flows’. These are memory item checks split between the pilot flying and pilot monitoring. The announcement to the dispatcher that they are clear to disconnect is the penultimate item. The last ‘flow’ item is for the flight crew to complete the challenge and response ‘after start checklist’. The last item on that five point checklist is confirmation that the dispatcher has been sighted clear of the aircraft. Only after completion of the ‘after start checklist’ should the crew request taxi clearance and turn on the taxi light. ATSB Analysis The ATSB explain that after the distraction of the aircraft on bay 5 the captain of VH-VGJ misidentified the dispatcher for the bay 5 aircraft as their own dispatcher. At this time, the tug, which would normally wait beside the departing aircraft for the dispatcher, had moved away from VGJ towards the terminal to avoid a conflict with the bay 5 aircraft. Therefore, the dispatcher sighted by the captain, was next to the tug used for the pushback of VGJ. This potentially provided an association between the tug and the dispatcher in the mind of the captain, who assumed the dispatcher had removed the nose wheel steering pin and moved away from the aircraft. The diversion of the flight crew’s attention away from their ‘after start flows’ probably resulted in the pilot flying not completing their memory items. This was not detected in the ‘after start checklist’ because the captain had misidentified the dispatcher for the bay 5 aircraft as the dispatcher for VGJ. Consequently, the dispatcher connected to VGJ was not cleared to disconnect prior to VGJ starting to taxi. ATSB Safety Message Following this serious incident the captain...
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