BFU Report on Dramatic Challenger Wake Vortex Accident
BFU Report on Dramatic Challenger Wake Vortex Accident Bombardier CL-604 Challenger D-AMSC dropped 9,000ft after a wake vortex encounter resulted in a temporary loss of control over the Indian Ocean. This resulted in two serious injuries (head injuries and a fractured rib in one case and a fractured vertebra in the other) andone minor injury. The airframe was overstressed and written off. The business jet, operated by MHS Aviation of Munich, was in the Mumbai FIR en route from Malé, Maldive Islands to Al-Bateen, UAE with 9 people on board on 17 January 2017. An Airbus A380, on an opposite course, passed over head 1,000ft higher, near the DONSA waypoint, around 500 nm from the nearest land. Less than one minute later the business jet hit the airliner’s wake. The Wake Vortex Encounter In their interim report the German accident investigation agency, the BFU, say the aircraft “shook briefly, then rolled heavily to the left and the autopilot disengaged”. The BFU explain that: At 0838:54 UTC the CL604, with engaged autopilot, began to slightly roll right. At the same time a counter-rotating aileron deflection was recorded and fluctuation of the vertical acceleration began. In the subsequent approximately 10 seconds the airplane had a right bank angle of 4° to 6°. At 0839:03 UTC the right bank angle began to increase. Within one second the bank angle increased to 42° to the right. At the same time the aileron deflection to the left increased to 20° and the vertical acceleration to 1.6 g. In the following second vertical acceleration changed to -3.2 g. The PIC [subsequently commented that] since the sky had been blue and the ocean’s surface almost the same colour he had been able to recognise the aircraft’s flight attitude with the help of the clouds. At 0839:04 UTC a lateral acceleration of 0.45 g to the right was recorded. The pitch angle changed from about 3° to about 1°, then within one second increased to 9° and decreased again in the following second to -20°. At the same time the FDR recorded a rudder deflection to the left reaching 11.2° after about two seconds whereas the bank angle changed from 42° right to 31° left. Between 0839:05 UTC and 0839:10 UTC Indicated Airspeed (in knots) changed from approximately 277 KIAS to 248 KIAS. The N1 of the left engine of 95% began to decrease. At 0839:07 UTC …the autopilot disengaged, and a master warning, lasting seven seconds, was recorded. Between 0839:09 UTC and 0839:41 UTC the FDR recorded a loss of altitude of approximately 8,700 ft. Large control surface deflections and acceleration were recorded. The speed increased and at 0839:31 UTC reached approximately 330 KIAS [vs a Velocity Maximum Operating (VMO) between 26,570 ft and 30,990 ft of 318 KIAS]. At 0839:30 UTC the spoilers extended and 13 seconds later were retracted again. The N1 of the left engine had decreased to approximately 40% when the Interstage Turbine Temperature (ITT) began to increase and nine seconds later had reached 850°. The left engine was shut off. [The] pilots had been able to recover the airplane at FL240 using control inputs on the aileron and later the rudder and slight elevator deflection. At about 0856 UTC the Pilot in Command (PIC) informed the air traffic controller in Mumbai of the occurrence, declared emergency…. At about 0915 UTC the crew restarted the left engine....
read moreCorrosion Found on an S-92A Flying Control Bracket
Corrosion Found on an S-92A Flying Control Bracket Corrosion was recently found on a flying control bracket of a 3 year old Australian Sikorsky S-92A, masking the attachment bolt torque value, according to a Service Difficult Report (SDR) submitted to the Civil Aviation Safety Authority (CASA) by an offshore helicopter operator. The operator reported: During routine inspection, it was found that one of the tail rotor pulley attachment bracket bolt has failed 100 in-lb torque check. Further investigation found FWD inboard anchor nut rivets had sheared – allowing the bolt to be somewhat tightened, but not able to be torqued. Aircraft is approximately three years old and no major maintenance has occurred in this area. The operator postulated that: …the main contributing factor was the finding that the bolts of the attachment were installed dry and light surface corrosion was found on the shank and within the bolt holes. The actions taken were: Anchor nut plate replaced, corrosion removed from all areas. All bolts, anchor nuts and mounting bracket treated with corrosion preventative compound. Sikorsky will be informed by established means. We previously discussed: S-92A Flying Control Restriction on Wiring Loom UPDATE 6 August 2018: In-Flight Flying Control Failure: Indonesian Sikorsky S-76C+ PK-FUP 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 moreFOD and an AS350B3 Accident Landing on a Yacht in Bergen
FOD and an AS350B3 Accident Landing on a Yacht in Bergen On 10 May 2017 Airbus Helicopters AS350B3 G-HKCN of HQ Aviation crashed into the sea while attempting to land on the 60m motor yacht Bacarella outside Bergen harbour in Norway during a private flight. All three persons on board egressed the helicopter. One passenger was transported to hospital. UPDATE 12 February 2019: The Accident Investigation Board Norway (AIBN – the Statens Havarikommisjon for Transport [SHT] in Norwegian) issued their final report. The helicopter had flown to Norway that day from the UK. The helicopter landed at Bergen Airport for refuelling where all three on board took off their survival suits and life jackets. The investigators explain that: The commander had valid British ATPL(H) with type rating for AS350B3 and flight instructor privileges. The person piloting the helicopter had a PPL(H), but no type rating for the helicopter type. He had had performed his skill test on AS350B3 the day before the accident. It was his first attempt to land an AS350B3 on the helideck. Landing on a helideck was not a part of any formal flight training programme. Thus, this was not a flight that formally required an instructor. As the helicopter approached the helideck on the yacht, it stopped in low hover over the helideck for approximately 15 seconds [then] a tarpaulin covering a jet fuel bowser located forward on the helideck detached and was blown up in the main rotor. The commander grabbed the controls and attempted to manoeuvre the helicopter aft and to the left to avoid the tarpaulin, which was on its way to blow into the main rotor due to the rotor downdraft. He did not have time to make a difference before the tarpaulin caused considerable damage to the main rotor when it encountered the rotor blades and was ripped to shreds. The damages to the main rotor caused significant vibrations in the helicopter. The commander lost control of the helicopter after the tarpaulin struck the main rotor. During this phase, both the commander and the pilot in the right hand seat had their hands on the controls. The helicopter ended up in the sea somewhat aft and port (left hand side) of the yacht with tail first and quickly tilted over to the right, before it came to rest upside-down. [The helicopter] remained floating upside-down. The commander, seated in the left hand seat, was able to quickly evacuate through the left door. Having exited the helicopter, he realised that the helicopter would sink and dived into the cockpit where he was able to activate the switch to inflate the floats [there was no Automatic Float Deployment System (AFDS) fitted]. The passenger in the rear seat was able to evacuate without assistance. The commander dived into the helicopter once more and assisted the pilot in the right hand seat to evacuate. It was this person that piloted the helicopter when the tarpaulin hit the main rotor. All three made their way up on the belly of the floating helicopter. The Norwegian Society for Sea Rescue 13m rescue craft Bjarne Kyrkjebø was coincidentally near-by and was able to make a quick rescue of the three people onboard the helicopter. One person is reported to have serious injuries and two had minor injuries. A video from shore is online. The helicopter was equipped with a Appareo Vision 1000 cockpit video and data recorder. This was...
read moreBell 429 TR Pitch Change Link Bearing Failure
Bell 429 Tail Rotor Pitch Change Link Spherical Bearing Failure On 21 August 2015, a privately operated Bell 429, N429AR, experienced an in-flight tail rotor pitch change link (PCL) failure and subsequently landed safely in Port O’Connor, Texas. The Accident Flight The US National Transportation Safety Board (NTSB) report that during cruise the pilot: …felt a “slight vibration” and heard a “very faint bumping sound.” A flight control check revealed no anomalies, and the pilot continued the flight to the destination heliport. While in a 4-ft hover, just before touching down, the helicopter began a slow, uncommanded right turn. The pilot applied full left anti-torque pedal, and the turn stopped. He then lowered the collective and landed without incident. Examination of the Helicopter The NTSB say in their report (and associated specialist report): A post-flight inspection of the helicopter revealed that one of the tail rotor outboard pitch change links (PCL) was broken. The tail rotor PCL assembly comprises a single-piece forged aluminum body with two circular ends (also known as the “banjo end”), each containing a spherical bearing (also known as a “mono-ball bearing”). One end of the tail rotor PCL is attached to the pitch change crosshead; the other PCL end is attached to its respective tail rotor blade pitch change horn. A total of four PCLs are installed on the four-bladed tail rotor of the Bell Helicopter 429: two short-length PCLs, identified as “inboard” PCLs, and two long-length PCLs, identified as the “outboard” PCLs, are used to accommodate the stacked rotor blade configuration. While no further damage was sustained to any helicopter components, the fractured tail rotor PCL had an adverse effect on the helicopter’s flight characteristics and required replacement, meeting the definition of substantial damage. The four tail rotor PCLs, the pitch horn associated with the fractured PCL, grounding cables, and attaching hardware were submitted by the operator for further examination. An examination of the failed PCL revealed fatigue fractures due to pitting corrosion between the spherical bearing and the bearing housing. The fatigue fractures propagated during operation until the PCL bearing housing fractured, separating the PCL from the blade pitch horn end spherical bearing, resulting in a loss of pitch control to the affected blade. Removal of the crosshead end spherical bearing revealed evidence of corrosion and fretting on the inner diameter surfaces of the [crosshead] circular end. The Maintenance History Maintenance records showed the fractured PCL was installed on the helicopter on February 6, 2015, at an aircraft total time of 1,062.9 hours. The helicopter had 1,241.9 hours total time at the time of the accident. The tail rotor PCLs had a total airtime of 179 hours… The PCL was installed on the helicopter 12 days before the manufacturer issued an alert service bulletin (ASB) introducing a 50-hour recurrent inspection of the tail rotor PCLs for axial and radial bearing play. Bell Helicopter ASB 429-15-16, issued on 18 February 2015 stated that: Bell Helicopter has received reports of tail rotor pitch link assemblies 429-012-112- 101/-103 with bearings 429-312-107-103 worn beyond the published limits and bearing liner failures. The inspection was estimated to take just 2 man hours and replacement of any degraded bearings about 3 man hours, with new bearings provided under warranty. The inspection was to be accomplished every 50 flying hours with a closing action at 200...
read moreGround Collision Under Pressure: Challenger vs ATV: 1-0
Ground Collision Under Pressure: Challenger vs ATV: 1-0 Bombardier CL-600-2B16 Challenger N613PJ, operated by Paragon Jets, ran over an all-terrain ground vehicle (ATV) at Palm Beach International Airport, Florida on 22 July 2015. Under Pressure The US National Transportation Safety Board (NTSB) describe in their final report that: According to the captain, the flight crew was under pressure from the operations department to continue to southern Florida to complete their flight and pick up customers that were waiting. In the telephone interview with the captain he said: …this aircraft has a long history of maintenance items and intermitted [sic] lights and warnings that have taken several months to correct and some still existing today. The aircraft had been in West Palm Beach for repairs after earlier defects. On the day they had: …waited for the flight attendant to show up and later found out that she drove down to southern Florida to meet that aircraft at the airport were the passengers were waiting. However, the Captain did not apparently feel that rushed that according to the co-pilot while she was “in the aircraft performing the checklist” he interrupted to ask “if she wanted to fly in the left seat”. Review of the CVR data did not reveal any tasks associated with the formal prestart checklist being completed. The CVR recorded a conversation about programming the flight management system and then it recorded the captain asking the first officer if she wanted to fly from the left seat. One minute later the first officer replied that she did want to fly from the left seat. The recorder then captured a conversation of an informal checklist usage along with a departure briefing. Two minutes later the recorder captured sounds consistent with both engines starting… Regular readers, with the added benefit of hindsight, will have recognised a number of threats and no doubt be wondering: What happened next? Ground Crew Intervention Two ground handlers, a supervisor and a trainee had noticed that the baggage door was open. They boarded an ATV and drove out to the aircraft… …parking about 10 feet in front of the left wing. One of the ground handlers then dismounted the ATV and proceeded in front of the airplane while motioning to the flightcrew in the cockpit that the baggage door was open. The captain then remembered that he forgot to close the baggage door and got up to go back and close the door. The door had been open anticipating the Flight Attendant arriving with luggage. Collision According to the Captain’s interview: Once closed he returned to his seat, on the right side, buckled his seat belt and picked up the checklist to start from where he left off. The NTSB say that “shortly after, the airplane began moving forward”: The ground handler then attempted to gain the attention of the pilot seated in the left seat, but was unsuccessful as that pilot never looked up. The airplane’s left wing then struck the ATV before it came to a stop. On the flight deck, the Captain “looked out the side window and noticed the plane was rolling forward”. The CVR had recorded: …sounds consistent with switch manipulation and shortly after the captain asked “what are you doing” with an immediate sound of a warning or alert tone as the captain stated, “no brakes….what are you doing?” the first officer responded, “ah...
read moreAW139 A6-AWN Ditching off UAE, 29 April 2017
AW139 A6-AWN Ditching off UAE, 29 April 2017 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. Details are limited but early reports suggest that the ditching was in response to apparent indications of a mechanical failure. All persons on board were recovered safely. The aircraft (MSN41213, a long-nose 139 built in the US in 2009) capsized before salvage. Common themes of the limited amount of (mostly 3rd hand) information available in the public domain describe MGB oil temperature rise and mechanical noise/vibration. MGB pressure loss or oil loss are not mentioned. Leonardo issued a statement to customers and other stakeholders on 1 May 2017. This occurrence is subject to investigation by the Air Accident Investigation Sector (AAIS) of the UAE General Civil Aviation Authority (GCAA). UPDATE 7 May 2017: It is being reported that the investigation is focusing on the oil cooler fan. In the EASA certification standard for large rotorcraft, CS 29.917 on design of rotor drive systems states (emphasis added): CS 29.917 (a) General. The rotor drive system includes any part necessary to transmit power from the engines to the rotor hubs. This includes gearboxes, shafting, universal joints, couplings, rotor brake assemblies, clutches, supporting bearings for shafting, any attendant accessory pads or drives, and any cooling fans that are a part of, attached to, or mounted on the rotor drive system. Hence the following rule applies: CS 29.917 (b) Design assessment. A design assessment must be performed to ensure that the rotor drive system functions safely over the full range of conditions for which certification is sought. The design assessment must include a detailed failure analysis to identify all failures that will prevent continued safe flight or safe landing, and must identify the means to minimise the likelihood of their occurrence. ‘Minimise’ is defined as applying ‘technically feasible and economically justifiable’ provisions. UPDATE 9 May 2017: The local press report that the helicopter had departed Abu Dhabi International Airport at 12.05, landed on one offshore installation at 12.31 before departing for a second. All POB are reported to have boarded the liferafts. UPDATE 12 June 2017: The GCAA Air Accident Investigation Sector (AAIS) has issued their preliminary report with commendable promptness: At 1233, the Aircraft departed from Dhabi II for BUNDUQ with a selected climb altitude of 2500 feet (ft). One minute into the climb, at approximately 490 feet (ft), the flight crew received a high oil temperature warning for the main gearbox. The observed oil temperature was 109°C. A review of data downloaded from the flight recorder shows that the oil temperature started to increase from the normal operation temperature of approximately 85°C, 1 minute 40 seconds prior to landing on the helipad of Dhabi II. The Aircraft landed with an MGB oil temperature of 102°C. By the time the Aircraft left Dhabi II, 1 minute 52 seconds later, the oil temperature had increased to 103°C. One minute 5 seconds after departing from Dhabi II, the MGB oil temperature reached to 109°C, at which point the MGB OIL TEMP warning alerted the flight crew to the exceedance in the MGB oil temperature. The flight crew decided to follow the QRH and divert to the nearest heliport on Mubarras Island. When the new destination was entered into the flight management system, the heliport was 14.9 NM away and the MGB oil temperature had increased to 114°C....
read moreSuper Puma Second Stage Planet Gear Background
Super Puma Second Stage Planet Gear Background The investigation into loss of CHC Helikopter Service Airbus Helicopters EC225/H225 LN-OJF on 29 April 2016 and the similarities to the 1 April 2009 Bond G-REDL AS332L2 Super Puma accident, has created interest in the second stage epicyclic planet gears used in later members of the Super Puma family. This article draws on a the most recent Accident Investigation Board Norway (AIBN – the Statens Havarikommisjon for Transport [SHT] in Norwegian) 102 page preliminary report on the LN-OJF accident, issued on 28 April 2017. Readers wishing to understand the wider gearbox architecture are advised to read Aerossurance’s article: EC225 Main Rotor Head and Main Gear Box Design We examined the wider aspects of the accident in our feature: EC225 LN-OJF Norway Accident Investigation Timeline Description of the Second Stage Planet Gear Layout The EC225/AS332L2 Main Gear Box (MGB) features two stages of epicyclic gear (shown in yellow and brown below). The second stage has eight planet gears (shown in the diagram below in purple), running between a sun gear (driven by the first stage epicyclic, shown in blue below) and a fixed outer ring gear (green below). The Second Stage Planet Gear consists of an outer gear (light grey/purple in the diagram above, right), bearing rolling elements and cages (turquoise and light grey respectively) and a bearing inner race (dark grey/green). The eight 2nd stage planet gears are mounted on a planet carrier that drives the main rotor. The Second Stage Planet Gear Design and Manufacture The AIBN explain that: The planet gear wheel without the bearing, including its rim and teeth, is designed and manufactured by Airbus Helicopters. The planet gear bearings were manufactured by FAG and SNR respectively following a Build to Specification process approved by Airbus Helicopters. For industrial reasons, the aim was to have two suppliers… …hence two bearing manufacturers were invited to tender for the AS332L2 planet gear bearings in 1986: The invitation specified a number of criteria. One such criterion was that it should be based on the existing design used in the AS 365 Dauphin gearbox, a gear already produced by FAG. Specifically, the focus was on limiting spalling on the inner raceway, as this had been a problem with the AS 332 L1. The planet gear, made from 16NCD13 steel, was classified as a “critical part”, i.e. a failure would be catastrophic and so subject to the extra requirements of certification requirement 29.602. Because the outer race of the planet gear bearing is integrated into the planet gear, a specific workshare is established between Airbus Helicopters and the bearing manufacturers. This workshare covers each phase of the design, the substantiation and the manufacturing process of the planet gear bearing. The design characteristics of the bearing inner race, rollers, cage and outer race finishing process are usually proposed by the bearing suppliers. Airbus Helicopters manufactures the planet gear wheel including the outer race and provides it to the bearing supplier with a partly finished bearing outer race surface. The supplier manufactures the bearing and performs the grinding of the planet gear outer race. Then, the supplier assembles the bearing and the planet gear wheels. The completely assembled planet gear including the bearing is supplied to Airbus Helicopters. The gears manufactured by FAG were given part number 332A32-3335-07 and gears manufactured by SNR part number 332A32-3335-06. Airbus Helicopters had approved that gears from both FAG and SNR could be mixed on a second stage planet gear...
read moreUnstabilised Approach Accident at Aspen
Unstabilised Approach Accident at Aspen On 5 January 2014 Bombardier CL-600-2B16 Challenger N115WF impacted the runway during landing at Aspen (ASE), Colorado (a “high-altitude, terrain-limited airport”). The copilot was killed and the captain and passenger received serious injuries. The US National Transportation Safety Board (NTSB) describe in their final report that: As the flight neared its destination…air traffic control (ATC) provided vectors to the localizer/distance measuring equipment (LOC/DME)-E approach to runway 15. About 1211, the flight crew reported that they were executing a missed approach and then requested vectors for a second approach. ATC vectored the airplane for a second LOC/DME-E approach to runway 15. About 1221, the local controller informed the flight crew that the wind was from 330° at 16 kts and the 1-minute average wind was from 320° at 14 kts gusting to 25 kts. The weather at the time of the accident was near or in exceedance of the airplane’s maximum tailwind and crosswind components for landing, as published in the airplane flight manual…: “the maximum tailwind component approved for take-off and landing is 10 kts.” The initial part of the airplane’s second approach was as-expected for descent angle, flap setting, and spoilers. During the final minute of flight, the engines were advanced and retarded five times, and the airplane’s airspeed varied between 135 kts and 150 kts. The final portion of the approach to the runway was not consistent with a stabilized approach. The airplane stayed nose down during its final descent and initial contact with the runway. The vertical acceleration and pitch parameters were consistent with the airplane pitch oscillating above the runway for a number of seconds before a hard runway contact, a gain in altitude, and a final impact into the runway at about 6 g. The NTSB say that both crew had low experience on type (the captain having no more than 14 hours): Airport surveillance video of the runway showed the airplane landing at ASE. The following sequence of events was seen in the video: the airplane above the runway in a slightly nose-down attitude, a flash of light consistent with a runway strike, the airplane in the air above the runway in a nose-down attitude, and the airplane impacting the runway in a nose-down attitude and being engulfed in light. About 4 seconds elapsed between the runway strike and the final impact. …performance calculations were completed to determine if the airplane could successfully perform a go-around. Assuming the crew had control of the airplane, and that the engines were advanced to the appropriate climb setting, anti-ice was off, and tailwinds were less than a sustained 25 kts, the airplane had the capability to complete a go-around, clearing the local obstacles along that path. The NTSB determined the probable cause to be: The flight crew’s failure to maintain airplane control during landing following an unstabilized approach. Contributing to the accident were the flight crew’s decision to land with a tailwind above the airplane’s operating limitations and their failure not to conduct a go-around when the approach became unstabilized. The NTSB also report that shortly after the accident the airport changed its procedures for dissemination of wind information: 1-minute average wind data was established to be the “official winds to be issued” to pilots at ASE. While the local controller provided the 1-minute wind...
read moreEASA Decisions on Management of Aeronautical Databases / Part-DAT
EASA Decisions on Management of Aeronautical Databases / Part-DAT The European Aviation Safety Agency (EASA) has recently issued two Executive Director (ED) Decisions on the management of safety-critical aeronautical navigation databases from 1 January 2019 onwards. This is a particularly topical development after the completeness of terrain databases was raised as a concern in the Irish Air Accident Investigation Unit (AAIU) preliminary report into the loss of Sikorsky S-92A EI-ICR, operated by CHC for the Irish Coast Guard as Rescue 116, at Black Rock off the coast of County Mayo on 14 March 2017. Background: Management of Aeronautical Databases At the 2003 FAA/JAA International Conference, it was agreed that an improved control of data held in aircraft navigational databases is essential as an enabler to support the implementation of the Performance-Based Navigation (PBN). Through Opinion No 01/2005, EASA offered the industry, via guidance material to Part 21, a voluntary quality system leading to the issue of a Letter of Acceptance (LOA) by the Agency to the European database suppliers. As the Opinion noted: The letter of acceptance will not attest that the data produced by these organisations can be used by operators, but that the organisation [the LOA holder] has put in place an appropriate quality system for the control of the processing of data. This will ease the obligation on the operator to do the same control and facilitate the issuing by the national competent authorities of the approval for the operators to fly in dedicated airspace where reduced separations are implemented. The final responsibility for the approval of operators for P-RNAV operations remains with the National authorities. There is no obligation on operators to buy their data only from organisations holding the letter of acceptance. Operators can either make the verifications themselves or use another competent organisation for this purpose and convince directly their responsible authority that they can be allowed to fly in P-RNAV airspace. The decision whether or not to apply for an EASA letter of acceptance is therefore entirely up to the navigation database supplier concerned. …the issuance of a letter of acceptance does not give any rights to its holder… This introduced two types of LOA: Type 1 LOA: where a Navigation Database supplier complies with EUROCAE ED-76 or Radio Technical Commission for Aeronautics (RTCA) DO-200A Standards for Processing Aeronautical Data, with no specific compatibility with a particular aircraft system. A Type 1 LOA holder cannot release navigation data directly to end users. Type 2 LOA: where a Navigation Database supplier complies with ED-76/DO-200A AND provides data compatible with specified avionics system(s). The Data Quality Requirements followed must be provided by, or agreed with, the specified equipment design organisation in accordance with a formal arrangement. A Type 2 LOA holder can release navigation databases directly to end users. They can also interface directly with data originators (such as State AIP providers and operators) and may use data supplied by a Type 1 LOA. In 2009, EASA’s remit was extended to ATM/ANS and this included a regulatory task to further address aeronautical information and data, hence this further work. Following the preparations started in 2009, on 1 March 2017 Commission Implementing Regulation (EU) 2017/3736 was adopted for common requirements for providers of Air Traffic Management (ATM) / Air Navigation Services and other ATM network functions and their oversight. Note: This also repealed (EU) 2016/1377 that had been ‘accidentally’ prematurely published prior to the completion of translation into all EU languages. On that matter of aeronautical data...
read moreAS365N3 Tail Rotor Pitch Control Loss During Hoisting
Tail Rotor Pitch Control Loss During Hoisting: Taiwanese NASC AS365N3 NA-107 The Aviation Safety Council (ASC) of Taiwan has issued its investigation report (in Chinese apart from an Executive Summary) into a fatal Survivable Water Impact (SWI) accident on 11 March 2016 involving National Airborne Service Corps (NASC) Airbus Helicopters AS365N3 Dauphin NA-107 during a transport hoist mission (shown in the video below). The Accident Flight On board were two pilots, one aircrew ‘crew chief’ and two Coast Guard Administration (‘CGA-SSC’) personnel to be transferred to a grounded cargo ship. On the day of the occurrence, at 1045 Taipei local time the aircraft successfully completed a first …transport mission [to the ship] and returned to Taipei Songshan Airport. After receiving the order for [a] return mission notice at noon, the flight crew did a crew briefing at 1237 and decided to…perform personnel hoisting (executed one person at a time and two times per [flight]). After arriving above the grounded cargo ship, the aircraft circled the cargo ship in clockwise direction…and began to approach the deck of the cargo ship. The crew chief began to perform the hoist mission, dropping off the [first] CGA-SSC member… The GPS system indicated that the aircraft began yawing towards the left at 1317:44. Four seconds later (1317:48), the aircraft began to turn drastically. According to the copilot’s interview, the aircraft was shaking in all directions as the aircraft drastically spun towards the left. The copilot also heard the pilot saying, “What is happening to the aircraft?” As the spinning speed of the aircraft accelerates, the CGA-SSC member [being hoisted] was thrown up by the great centrifugal force generated by the spinning motions and aircraft altitude change. After the CGA-SSC member impacted the main rotor and crashing into the sea, the aircraft plummeted on the sea surface to the left of the cargo ship at 1317:59 with a right roll in an easterly direction. The helicopter was destroyed. The aircraft commander’s cause of death was abdominal bleeding and drowning and the hoist passenger were killed upon after the main rotor blade strike. The other occupants sustaining serious injuries. The helicopter’s emergency flotation system was deployed but the aircraft impacted on its right side. The front right bag did not inflate due to impact damage. The internal cabin life raft was not deployed. The three survivors all escaped underwater from the capsized helicopter and clung to the belly until rescued. The passengers were not equipped with life jackets and the commander had a non-issue ‘lightweight’ life jacket. Sea temperatures at that time of year are typically 20°C. The survivors were rescued within an hour. The aircraft was not fitted with a Flight Data Recorder (FDR) or a Vibration Health Monitoring (VHM) / Health and Usage Monitoring System (HUMS). The Safety Investigation The fenestron control rod double bearing (item 17) was subject periodic inspection in accordance with the Alert Service Bulletin AS365-05.00.61R4 (EASA Airworthiness Directive 2012-0170R2), which had evolved after a couple of prior loss of yaw control events (and 8 prior degraded bearings in total). Wear of the SKF manufactured bearing continued and eventually led to a loss of tail rotor pitch control after the inner race retaining shoulder rapidly deteriorated. Five of the twelve ball bearings on one side had been released (all were undersized due to wear). Laboratory examination confirmed the bearing...
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