Why a Collective Control Came Loose in a Pilot’s Hand…
Why a Collective Control Came Loose in a Pilot’s Hand… (French Army ALAT Tiger) On the afternoon of 22 March 2021 French Army Airbus EC665 Tiger (Tigre) HAP s/n 2002 of the 5th Helicopter Combat Regiment (5e RHC) was engaged in an area reconnaissance training mission at Castres Le Pesquié. The helicopter had flown to the exercise area from its base at Pau that morning. Investigators of the BEA-Etat (BEA-E) explain in their safety investigation report (issued in French only) During transit to the exercise area, in visual flight at around 500 feet, the pilot in the front seat detected a fault on the collective stick. Holding this handle with his left hand, he notices during a vertical movement that one of his fingers rubs against the seat to the right of the handle, which is unusual. Very surprised, he warned the captain in the rear seat while realizing that the collective stick was moving abnormally in rotation around its axis. The captain in the rear seat decided to cancel the mission, took control of the helicopter and landed safely five minutes after takeoff. Subsequent inspection revealed that the top of the front collective pilot stick (1) could be separated from the lower tube (8) by simply pulling in the axis of the tube. The design is such that there is a cover (7), bolt (6), washers (4 and 5), nut (3) and pin (2). The screw was fitted through the stick and the cover but crucially it did not pass through the holes in the lower tube. The last recorded maintenance on the collective occurred on 28 October 2020, 53 flying hours and almost 5 months earlier. The BEA-E report that the task: …was carried out by a novice technician who had obtained the level 1 technical certificate (CT 1) but was awaiting a type rating course on EC665. The French Army practice is for technicians to gain 6 months of hands on maintenance experience before undertaking a type course. The French FR-145 military aviation maintenance regulations are based on EMAR-145, itself derived from EASA Part-145, so effectively this was a newly qualified A Licenced engineer. He was performing this maintenance operation for the first time, under the supervision of a team leader. The latter considered that the installation of the collective pilot stick was a simple operation with no possibility of error. The technician was given the work card for the task. The team leader remained present during the operation. However, he had no direct view of the actions of the technician during the fitment of the collective pilot stick due to the narrowness of the Tiger’s cockpit. He then checked the assembly a posteriori. At the end, the controller cross-checked the entire maintenance intervention on the flying controls as planned. He did not detect any improper installation of the collective pilot stick. The BEA-E believe it was during this task that the misassembly occurred. Crucially, the BEA-E describe the work card as “succinct”. While conciseness is usually a good thing, in this case the work card “did not present a detailed method for checking the conformity of the installation”. In particular, this was not identified a a critical task, while other tasks that had to be checked by the controller were. The BEA-E explain if the bolt was misaligned, then the cover would sit 6-8 mm proud rather than being flush. This is the distance between fitting the bolt through hole in both tubes and fitting it...
read moreHelicopter / Drone Mid Air Collision Filming Off-Road Race
Helicopter / Drone Mid Air Collision Filming Off-Road Race On 6 February 2020, Airbus Helicopters AS350BA N611TC of Icon Helicopters and a 0.9 kg DJI Mavic 2 Zoom drone collided in mid air during filming of the King of the Hammers off-road race in the Johnson Valley, in the High Desert of San Bernardino County, California. The helicopter escaped with scratches to its windscreen but the drone crashed after a motor arm severed. The US National Transportation Safety Board (NTSB) issued their safety investigation report into this mid air collision on 6 January 2022. The King of the Hammers event is part of the Ultra4 Racing series. The event production company, Hammerking Productions Inc, outsource the management of the video production to a contractor. Its that organisation that then hires in helicopter and UAS operators. The NTSB note that: Five helicopters and four drones were contracted to cover the event. The incident helicopter was operated under Part 91 with an FAA Certificate of Authorization or Waiver to 14 CFR 91.119(b) and (c) for low altitude TV and motion picture filming. The helicopter pilot had 4200 hours of experience including 10 years filming similar events (which suggests the age listed in the NTSB report [20] is incorrect) The incident drone had been leased by the production company from Lens Rentals and was being operated under a “verbal contract” by a 44 year old individual under Part 107 regulations. They had gained their FAA Remote Pilot Certificate in February 2019 and had 90 hours of experience. The NTSB explain that: Event organizers provided pre-race information to the helicopter pilots which included…the flight times and schedule for the race, insurance information, procedures for clearing the course of unauthorized persons, and helicopter landing zones and radio frequencies. They provided a Google Earth kmz map including details of the course and locations [too]. According to race management, the locations of the drones indicated on the map were not containment zones but were meant as an indication of the locations where they would have network connection to transmit the video feed. Organizers stated the drones were limited to less than 400 feet (note: this is in accordance with 14 CFR Part 107) and helicopters were required to remain above 500 feet in areas of spectators (note: this is generally in accordance with 14 CFR Part 91). The area of the collision was not accessible by spectators. A pilot meeting was held on February 2, including helicopter pilots and event management. It did not include the drone pilots. The NTSB report the incident drone pilot (or Remote Pilot-In-Charge [RPIC]) “did not have any operating manuals or checklists for the operation”. They also told the NTSB that, unlike the helicopter pilots, they were not given any event maps. The incident pilots were not in communication with each other, nor was there any provision or requirement to do so. The helicopter pilots covering the course communicated with each other via a common air-to-air frequency. The drone pilots did not use or monitor radio communications. The NTSB recount that: Video from the drone, and the accounts of each pilot, indicate the two aircraft were following a vehicle climbing an undulating dirt track in hilly canyon terrain. Video showed the helicopter visible in the drone camera (which was displayed on the drone pilot’s screen) above and to the right of the drone. The drone continued to follow the vehicle toward the position of the helicopter. As the track turned to the right, the helicopter passed...
read morePedestrian Seriously Injured by Air Ambulance Landing at Melbourne Hospital
Pedestrian Seriously Injured by Air Ambulance Landing at Melbourne Hospital (AW139 at The Alfred Trauma Centre HLS) The Australian Transport Safety Bureau (ATSB) report that on 28 October 2021, while a Leonardo AW139 air ambulance helicopter was landing at The Alfred Hospital Helicopter Landing Site (HLS) in Melbourne, Victoria a passer-by walking along Commercial Road, under the approach path, was blown over and seriously injured. ATSB identify neither the helicopter registration nor the operator. Ambulance Victoria contract five AW139s. The 39 by 42 m elevated Alfred’s HLS opened in 1988 as part of the development of Australia’s first dedicated trauma centre, instituted as part of a programme to tackle major road injuries in particular. It has been claimed that the availability of this centre, one of only two adult trauma centres in the state, has reduced the road traffic death rate by 50% in the state (VIDEO 1). The ATSB explain that: The crew approached the helipad from the west [at about 15:50 Local Time], using a steep approach profile aligned with Commercial Road. There does not appear to have been any subsequent assessment of FDR data to verify the approach. The pedestrian was “about 50 m” to the west of the HLS when they were blown over. The Alfred HLS is located on an elevated platform approximately 8 m above Commercial Road, a publicly accessible thoroughfare with both vehicular [road and tram] and foot traffic. This design is unique in Australia, exposing public vehicles and pedestrians to the possibility of helicopter downwash on landing. VIDEO 2: B412 approach and landing at The Alfred Hospital HLS from the west Previously helicopters had landed in Fawkner Park on the opposite side of Commercial Road. The elevated site was given a A$250,000 lighting upgrade in 2021. The ATSB also comment that they have… …received reports of 5 rotor wash events at various hospital HLSs since 2016. Of these, 3 occurred at The Alfred hospital HLS and all involved AW139 helicopters. After the incident the helicopter operator temporarily ceased operations from the site. They only recommenced operations after they had: Reduced the maximum number of helicopters on the helipad from two to one, removing the requirement to hover taxi away from the centre of the helipad Implemented pedestrian marshalling procedures for all helicopter movements, so that operations will only occur when no pedestrians are within 30 m of the helipad. The hospital has also commissioned a study of the site. Local HLS Regulations and Standards In Australia, CASA CAAP 92-2(2) provides ‘Guidelines for the establishment and operation of onshore Helicopter Landing Sites'(last updated in 2014). The Victorian Health Building Authority (VHBA) also publish Guidelines for helicopter medical transport landing sites Issued June 2020 and rebranded in June 2021). VIDEO 3: AW139 take off from The Alfred Hospital HLS to the west: VIDEO 4: AW139 take off from The Alfred Hospital HLS to the west VIDEO 5: B412 take off from The Alfred Hospital HLS to the north ATSB Safety Message Helicopters produce significant main rotor downwash, especially during hover taxi, take-off and while approaching to land. It is important that the risk of downwash related injuries, either by direct exposure or by being struck by loose items, be assessed prior to using a helicopter landing site (HLS). As pilots have limited ability to reduce rotor downwash during these phases of flight, securing loose items in the vicinity of the HLS and keeping people a safe distance away are the most...
read moreAir Ambulance Helicopter Struck Ground During Go-Around after NVIS Inadvertent IMC Entry
Air Ambulance Helicopter Struck Ground During Go-Around after NVIS Inadvertent IMC Entry (Mercy Flight, Bell 429, N505TJ) At 21:10 Local Time on 6 October 2021 air ambulance Bell 429 N505TJ of Mercy Flight was damaged near Genesee County Airport, Batavia, New York (midway between Buffalo and Rochester). Neither the pilot or the three medical personnel onboard were injured. Mercy Flight are a not-for-profit air ambulance operator that have transported 30,000 patients over 40 years. The Accident Flight Information released by the US National Transportation Safety Board (NTSB) in their public docket on 4 January 2022 reveals that the aircraft had been tasked to collect a patient and deliver them to Strong Memorial Hospital, Rochester, New York. A short 10 minute third sector was necessary to return to their home base at Batavia-Genesee County Airport. The pilot had been flying for 30 years, including flying for a Police Department, and most recently had flown for Mercy Flight for 5 years. He had flown 3583 hours in total, 621 on type and 1049 at night. He held an Instrument Rating. His instrument experience consisted of 11 hours actual and 49 simulated. He was working his usual 20:00-0800 shift and woken at 17:00 after a “good night’s rest”. All three sectors were conducted using a Night Vision Imaging System (NVIS) and Night Vision Goggles (NVGs) in what were stated to be Visual Flight Rules (VFR) conditions. The pilot had checked the weather before the first sector but did not recheck at Strong Memorial Hospital “because it was clear”. The automated data at 20:50 for their destination was cloud at 1400 ft and 10 mile visibility, 10ºC air temperate and a dew point at 9ºC . As the helicopter neared the airport several occupants noticed “patches of fog” which they discussed over the intercom according to an interview with the pilot. Curiously the brief narrative in the accident report form appears to contradict that by stating that no one onboard saw “the isolated fog bank” (although could relate to a specific patch of fog). Once the airport was in sight the pilot terminated the radar service and self-vectored for “a practice RNAV-28 LPV approach, under VFR”. In interview with the FAA the pilot reported that the 4-axis autopilot was coupled and that the “runway and lighting was in sight all the way down the glideslope”. The pilot stated he “did not notice the fog” through the NVGs. The FAA interview states he did not ‘look under’ (i.e. below) the googles and it is surprisingly stated that looking below was “not normal”. This was not apparently challenged by the FAA interviewers. An FAA interview summary then states: At about 200 feet, he inadvertently entered a fog bank and lost visual reference to the runway. According to comments by the operator on the accident form, the pilot decided to hand-fly the aircraft “because of the close-proximity to the ground”. However: He attempted a climbing right turn to exit the fog, but forgot to totally de-couple the autopilot. He was able to momentarily climb above the fog, but was fighting the autopilot for control, and the aircraft descended back down into the fog bank, while drifting north. During the attempted go-around, he made a radio call announcing the loss of visuals. Helicopter did not seem to be climbing as he pulled in collective. He managed to keep the aircraft level, and about...
read moreFatal ATC Handover: A Business Jet Collides with an Airport Vehicle on Landing
Fatal ATC Handover: Challenger 300 9M-TST Collides with an Airport Vehicle on Landing at Kuala Lumpur-Sultan Abdul Aziz Shah Airport (Subang) On 18 March 2019 Bombardier BD-100-1A10 Challenger 300 9M-TST of Berjaya Air, with 12 persons on board, was damaged when it struck an engineering vehicle when landing at night at Kuala Lumpur-Sultan Abdul Aziz Shah Airport (Subang) (SZB). The driver of the vehicle died later in hospital due to head injuries. The Malaysian Air Accident Investigation Bureau (AAIB) explain in their safety investigation report (issued 2 December 2021) that the aircraft had made an ILS approach and touched down at 03:11 Local Time and was decelerating through 100 knots when the aircraft commander felt an impact. The aircraft stopped on a taxiway and the cabin crew confirmed that they could see damage to the wing. The aircraft commander the proceeded to taxi to their stand. No one onboard was injured. On inspection there was significant damage to the left hand wing with embedded debris from the Perodua Kembara SUV that was hit. The SUV was found 1200 m from the runway threshold by the airport fire crew. Its roof was ripped off and the the driver was trapped inside. The AAIB Safety Investigation The SUV had been escorting a runway painting vehicle (with three occupants) that had been authorised to enter the runway at 01:00 Local Time to paint centre line markings, 10 minutes after a separate electrical working party had been cleared to conduct runway lighting work. The Duty Air Traffic Controller had radio communications with the escort vehicle not the painting contractors vehicle. There were two controller shift changes: However, in the handover between ATC shifts at 03:00 Local Time there was no mention of ongoing work. Although there was a written record of the work commencing, when the electrical working party left the runway at 02:15 Local Time the log recorded that all vehicles were clear. The team leader on the painting vehicle did see the landing lights of the business jet on approach. Fearing of the danger, all three workers boarded their vehicle and drove away from the runway. While making a 180 degrees turn, the driver realised the escorting vehicle was still static [about 120 m away]. …they flashed the headlights of their vehicle several times to attract the escort vehicle attention. No response was observed from the escort vehicle, and as the aircraft was getting closer to them, the [painting vehicle] driver drove…away from the runway and stop[ped] at taxiway Foxtrot to give way for the aircraft to land. The escort vehicle (only) was fitted with an amber flashing light. Neither the ATCO nor the flight crew saw the light which the painting crew confirm had been on. It was also not visible when CCTV footage was examined. As the light was destroyed the investigators could not determine its intensity or whether it was still operating at impact. The investigators explain that: ATC services [are] provided by Civil Aviation Authority of Malaysia (CAAM). The Aerodrome Control consist of Tower Supervisor, Aerodrome Control, Surface Movement Control, Assistant Surface Movement Control and Assistant Tower/Coordinator. During the time range of before and after the accident, Aerodrome Control manning have been reduced to one controller per shift for one and a half hour on each rotation from 0001hrs until 0600hrs in a system named as “Break Shift”. The...
read moreFiery Fatal AW119 Accident in Russia After Loss of Tail Rotor Control
Fiery Fatal AW119 Accident in Russia After Loss of Tail Rotor Control (RA-01908) On 30 December 2018 four people died when privately operated Leonardo AW119 MII Koala RA-01908 crashed near Ulan-Ude in Eastern Siberia. The IAC/MAK safety investigation report (issued 22 November 2021) explains that while attempting to land at the village of Berezovka on a football pitch: An eyewitness saw…the helicopter began to gain altitude over the football field. In the climb, the helicopter began to rotate clockwise, moving towards the forest. The helicopter crashed in the forest and caught fire. The occupants were ejected from the fuselage (the investigators believe they were not wearing their seat belts). The signal from the helicopter’s Emergency Locator Transmitter (ELT) was not received. Safety Investigation At c 01:45UTC (09:45 Local Time) the pilot appears to have decided to return to their departure point. The helicopter had already deviated from the straight line route to their intended destination (in pink below) and the helicopter had “made vigorous maneuvering, including when flying at an extremely low altitude of ≈ 50 m at a speed of less than 50 km / h”. During such manoeuvres, the load on the tail rotor would have been high. The investigators speculate this could have been some form of fault-finding after the pilot detected an abnormality, though we observe that they may have been done for some other reason and this would have accelerated the damage investigators subsequently found. Certainly no distress call was made and no difficulties mentioned in radio communication. At 02:18 the aircraft started to descend to make an landing on a football pitch. This was a more open area than the private landing site at the helicopter’s base. It got to less that 30 ft above the pitch before climbing. The witness saw it rotate around its axis as it rose to 350 ft or more and drift over the adjacent forest before it then crashed. During examination of the wreckage it was identified that the duplex bearing of the Tail Rotor Pitch Change Shaft had failed and the cover that serves as the end cap of the mechanism was missing. According to investigators, further examination showed that, most likely during maintenance by Ural Helicopter Company, one of the two inner race had been installed in reverse, lengthening the assembly. Examination of the work cards for past 100 hour tail rotor related inspections show that those due at 500 and 700 flying hours were not done (the accident occurred at 701.1 hours). The investigators suspect that there was a misunderstanding that if a tail rotor balance (item 12a on the work card) was not done then the inspection (12b) also was not required. The investigators are confident that if the cover was missing it would have been spotted ore-flight and so concluded it must have been released in flight. The misassembly would have resulted in applying a load to unscrew the retaining nut that resulted in “abnormal control input on the tail rotor blades that may have caused the loss of control in yaw of the helicopter”. The nut should however be spilt pinned, suggesting a further maintenance error. Leonardo’s specialists comment that initially the bearings would have been kept in place due to thermal expansion but they could not withstand the axial load indefinitely and the wear rate would accelerate. Investigators comment that: Most likely, in the process...
read moreSnagged Sling Line Pulled into Main Rotor During HESLO Shutdown
Snagged Sling Line Pulled into AS350B3 Main Rotor During HESLO Shutdown (Mount Difficult, VIC) The Australian Transport Safety Bureau (ATSB) report that on 20 June 2021, an Airbus Helicopters AS350B3 was damaged and a ground crewmember injured at the end of Helicopter External Sling Load Operations (HESLO) on Mount Difficult, near Horsham, Victoria. ATSB identify neither the registration nor the operator. The helicopter was being operated single pilot with a 100 ft long line, supported by a second pilot acting as ground crew. The two pilots had worked extensively together, swapping roles, during the unspecified project. We note that a 20 year A$33.2 million project to create a 160 km trail along the spine of Victoria’s Grampian range, past Mount Difficult, was opened in November 2021. The helicopter had completed the 8 lifts required that day and at 1350 Local Time returned to the Helicopter Landing Site (HLS) near the worksite. The ATSB explain that the HLS was… …was a confined area on the edge of a rock ledge with trees and shrubs nearby. The established procedure was to lower the remote hook and line to the ground before releasing the line from the belly of the aircraft at the lowest safe height. The helicopter would then reposition for an approach. This allowed the helicopter to approach the HLS without the 100 ft line attached. The pilot placed the line to the south of the HLS and re-positioned to land. Most of the line was lying on the ground, but a small section of the line was suspended in a sapling 10–12 ft right front of the aircraft nose. The aircraft landed clear of the line, and after receiving confirmation from the ground crew member that the landing position looked safe, the helicopter was shut down. As the engine spooled down the ground crew member commenced sorting and coiling the line into the back of the aircraft. This placed tension on the line between the coiled section in the helicopter and the looped section in the tree, thereby bringing the line into the path of the rotor disc. This was caught by a blade and subsequently entangled the rotor head. The line pulled the ground crew member’s arm upwards, snared their lower leg and body, before pulling them sideways along the ground. The crew member sustained minor bruising to their face, right elbow, left leg and foot and was later cleared of concussion or serious injury. The line was later found to have wrapped around the mast, resulting in minor damage to the swashplate, mast, rotor head and main rotor blades. Safety Actions After the incident a safety briefing was conducted with all the operators pilots “which included an incident analysis, review of procedures and safety measures”. The ATSB report that “a new requirement was introduced that now states that objects should not be raised above shoulder height while under the rotor disc”. While that seems of low connection to the incident, as reported by ATSB the operator also updated their Operations Manual, Daily Safety Briefing and Emergency Plan) to clarify that: movement of equipment, including aerial work equipment, into and out of aircraft should be conducted while the rotor is stationary unless strictly necessary; and coiling of lines and the assembly of equipment must be completed outside the rotor disc unless the rotor is completely stationary. Our Observations This is a good example of never letting...
read moreAir Methods AS350B3 Air Ambulance Tucson Tail Strike
Air Methods AS350B3 Air Ambulance Tail Strike at Tucson Medical Center, AZ (N544AM) On 16 October 2021 an Air Methods Corp (AMC) helicopter air ambulance Airbus Helicopters AS350B3, N544AM, suffered a tail rotor strike on landing on an elevated helidpad at Tucson Medical Center, Arizona. The four occupants were uninjured. The US National Transportation Safety Board (NTSB) has released a brief preliminary report and (on 21 December 2021) a short public docket. The helicopter was transporting a patient in daylight from Nogales, Arizona. The pilot had flown 3188 hours, 161 on type. As the helicopter came over the elevated helipad the tail rotor contacted the handle of a large wheeled fire extinguisher. What is noticeable is the extinguisher potion and that the helicopter had landed significantly off centre. The satellite imagery shown in Google Maps suggests this is not uncommon. Furthermore the extinguisher, which the satellite imagery above suggests is normally in this location (albeit with no apparent ready access or safe space for any waiting ground personnel), is only marginally higher than a series of metal handrails around the helideck shown below. There is no perimeter netting to minimise obstructions as is common elsewhere (e.g.: UK CAA CAP1264: Standards for helicopter landing areas at hospitals). One would hope the safety investigation considers the layout of hospital’s heliport and the adequacy of the design standards used. As seen above, not only was the tail rotor damaged but debris impacted the tail boom and punctured the horizontal stabiliser. In 2017 the FAA changed Part 135 so that helicopter air ambulance operators have to comply with a new Flight Data Monitoring (FDM) System requirement, FAR 135.607. FAA AC 135-14B Helicopter Air Ambulance (HAA) Operations explains that the system… …should record digital or analog raw data, images, cockpit voice or ambient audio recordings or any combinations thereof which ideally yield at least the following flight information: • Location; • Altitude; • Heading; • Speeds (airspeed and groundspeed); • Pitch, yaw, and roll attitudes and rate of change; • Engine parameters; • Main rotor RPM; • Ambient acoustic data; • Radio ambient audio; and • Any other parameter the operator deems necessary (e.g., high definition video recording looking forward including instrument panel and forward cockpit windshield view, intercommunications system (intercom) between pilot and medical crew, communications with air traffic control (ATC), OCS, base operations, first responders at scene, hospital, etc.) So a competent and comprehensive safety investigation would have access to extensive data, and other non-volatile memory data (such as GPS data) from the aircraft too, to evaluate the approach and determine the effectiveness of the FDM program in routinely monitoring approaches and providing constructive feedback to crews. NTSB Probable Cause (UPDATE: 29 April 2022) The NTSB issued this laughably un-insightful probable cause: The pilot’s failure to maintain clearance from ground equipment during landing. Safety Resources The European Safety Promotion Network Rotorcraft (ESPN-R) has a helicopter safety discussion group on LinkedIn. You may also find these Aerossurance articles of interest: Air Ambulance B407 Hospital Helipad Deck Edge Tail Strike During Shallow Approach South Korean Fire-Fighting Helicopter Tail Rotor Strike on Fuel Bowser Air Methods AS350B3 Night CFIT in Snow NTSB on LA A109S Rooftop Hospital Helipad Landing Accident Air Ambulance Helicopter Fell From Kathmandu Hospital Helipad (Video) US Air Ambulance Near Miss with Zip Wire and High ROD Impact at High Density Altitude Air Ambulance Helicopter Downed by Fencing FOD Ambulance / Air Ambulance Collision Beware Last Minute...
read moreR44 “Unanticipated Yaw” Accident During Tailwind Take Off Caught on Video Say NTSB
R44 “Unanticipated Yaw” Accident During Tailwind Take Off Caught on Video Say NTSB(N3264U) On 20 December 2020 Robinson R44 N3264U crashed at Morris Municipal Airport/Washburn Field, Illinois The pilot received minor injuries. In their safety investigation report the US National Transportation Safety Board (NTSB) explain that the pilot has 1650 hours of flying experience, 280 on type. There were three weather observations recorded from around the accident time and the wind was from 240° to 250° at 6 to 7 knots, with no reported gusts. The pilot was practicing “pickups and set downs in the same spot on the ramp and the wind was from the west as he completed these maneuvers. During the final maneuver, the wind shifted, and he lost control of the helicopter”. An airport surveillance video showed that during accident sequence, the helicopter was facing east when it briefly touched down and wobbled, then lifted up as the tail boom swung around in a clockwise direction. The tail rotor impacted the ramp then climbed and continued to rotate. The helicopter completed about 1.5 rotations as it descended and impacted the ground and rolled onto its right side. The tail rotor struck the ground early in the sequence. NTSB note that Robinson issued a safety notice on unanticipated yaw in May 2013: A pilot’s failure to apply proper pedal inputs in response to strong or gusty winds during hover or low-speed flight may result in an unanticipated yaw… To avoid unanticipated yaw, pilots should be aware of conditions (a left crosswind, for example) that may require large or rapid pedal inputs. Practising slow, steady state hovering pedal turn will help maintain proficiency ibn controlling yaw. Hover training with a qualified instructor in varying wind conditions may also be helpful. NTSB Probable Cause The pilot’s inadequate pedal application during liftoff with a tailwind, which resulted in a loss of yaw control and a subsequent impact with terrain. Or was this simply mishandling? Watch the video and make your own decision! Safety Resources The European Safety Promotion Network Rotorcraft (ESPN-R) has a helicopter safety discussion group on LinkedIn. You may also find these Aerossurance articles of interest: Unanticipated Yaw: Loss of Control During Landing Site Survey Grand Canyon Air Tour Tragic Tailwind Landing Accident Inexperienced IIMC over Chesapeake Bay: Reduced Visual References Require Vigilance US Air Ambulance Near Miss with Zip Wire and High ROD Impact at High Density Altitude Fatal Wisconsin Wire Strike When Robinson R44 Repositions to Refuel Impromptu Landing – Unseen Cable A Try and See Catastrophe: R44 Accident in Norway in Bad Weather Fatal B206L3 Cell Phone Discount Distracted CFIT Tragic Texan B206B3 CFIT in Dark Night VMC Fatal Wisconsin Wire Strike When Robinson R44 Repositions to Refuel Fatal R44 Loss of Control Accident: Overweight and Out of Balance Latent Engine Defect Downs R44: NR Dropped to Zero During Autorotation Helicopter Destroyed in Hover Taxi Accident Firefighting AW139 Loss of Control and Tree Impact UPDATE 9 July 2022: R44 Ditched After Loss of TGB & TR: Improper Maintenance Airbus have discussed unanticipated yaw phenomena and the ‘myth of LTE’ here: Aerossurance has extensive air safety, operations, SAR, 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 moreDutch Maritime NH90 Caribbean Accident: Focus on the Survivability Issues
Dutch Maritime NH90 Caribbean Accident: Focus on the Survivability Issues On 19 July 2020, a Royal Netherlands Navy NHIndustries NH90 NATO Frigate Helicopter (NFH) N-324 was destroyed in a water impact in the Caribbean off Aruba. The accident occurred alongside the Holland-class offshore patrol vessel HMNLS Groningen during a series of deck landings to keep the ship’s flight deck officer current. Two of the four crew died. The aircraft, which capsized and initially floated inverted, sank the next day after the forward flotation bags deflated. The Dutch Safety Board (DSB or Onderzoeksraad) issued a safety investigation report (in Dutch only) on 9 December 2020. They concluded a water impact occurred after airspeed reduced during the downwind leg with insufficient power input at a height that prevented recovery (a Loss of Control-Inflight [LOC-I]). They also highlighted survival issues associated with the two fatalities. Just 3 days later we published our analysis of the DSB to highlight some of the important lessons: NH90 Caribbean Loss of Control – Inflight, Water Impact and Survivability Issues. The Defence Safety Inspectorate (IVD) have now published their deeper investigation report (issued, again in Dutch only, on 2 December 2021). The IVD confirmed the DSB conclusions and make 5 safety recommendations. In this article we are going to concentrate on the survivability aspects. The Water Impact and Capsize On the eighth flight the helicopter did a lower circuit than before, less than 100 ft, as the plan was to take photos of the ship. The ship was steaming at just 3 knots in a direction of 108º and the wind was from 100º and 20-25 knots. The waves were 3 m high, the air temperature 31ºC and the sea temperature 29ºC. The helicopter passed down the right-hand side of the ship downwind: Because the ground speed was kept almost constant at 38 knots during the turn and the helicopter turned to downwind (with a tailwind), the airspeed decreased. With decreasing speed below 80 knots, more power was needed to keep flying horizontally at the same height. The helicopter started to descend with the descent speed initially increasing to about 370 feet per minute (fpm) at a height of 67 feet (about 20 meters) above the water’s surface. It is unclear whether the crew was aware that speed and altitude were decreasing. One second before the helicopter had descended to 67 feet, the pilot gave a forward input to the cyclic stick and then reduced power by 24 percent by moving the collective down. This further increased the rate of descent to 1,360 fpm and it became inevitable that the helicopter would hit the water. Upon impact the tail broke away. The IVD say that the simultaneous shift in CG and the loss of tail rotor torque meant the aircraft overturned “almost immediately”. The emergency flotation system was armed and automatically deployed, so the aircraft remained floating inverted. Crew Positions, Aircrew Equipment Assembly (AEA) and Cabin Safety Equipment There were four occupants on board at the time of the accident; in the front sat a pilot as captain (Pilot in Command, PIC) and a Tactical Coordinator (TACCO), in the back sat a Helicopter Sensor Operator (HSO) and a Rescue Operator Airborne Marksman (ROAM). The helicopter was configured as standard for an operation in the Caribbean at the time of the accident. In the cabin, near the right cabin door, there was a gun mount with an automatic weapon on...
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