Improvised Ice Road IMC Approaches – Twin Otter CFIT
Improvised Ice Road IMC Approaches – Twin Otter CFIT (Air Tindi C-GMAS) On 27 December 2023, Air Tindi De Havilland DHC-6 Twin Otter 300 C-GMAS crashed into the crest of a snow-covered hill during an approach to an ad hoc airstrip at the Lac de Gras road camp, Northwest Territories during a visual flight rules flight. The two pilots and 8 passengers survived, two with serious injuries The Transportation Safety Board of Canada (TSB) released their safety investigation report on 8 January 2026. Air Tindi was founded in Yellowknife, in 1988 and operates a fleet of 17 single- and multi-engine turboprop aircraft according to the TSB. The Accident Flight That morning the Twin Otter had flown from Yellowknife, to Margaret River and was to fly on to Lac de Gras, near the Diavik diamond mine site, before returning to Yellowknife. The aircraft was transporting Tibbitt to Contwoyto ice road construction workers and supplies to temporary camps at Margaret Lake and Lac de Gras. The Aircraft Commander (who had c14,300 total hours, c 8,000 on type) would be the Pilot Flying (PF) for the first 2 legs (i.e. to the two ad hoc air strips), and the co-pilot (c400 total, c 200 on type) would be the Pilot Monitoring (PM). The FO was a former dispatcher with the operator, who became a part-time FO on the Twin Otter on 1 August 2023 (5 months before) and only started a full-time flying position on 17 November 2023 (c 6 weeks before). The aircraft was equipped with 2 Garmin GNS 430W GPS (global positioning systems) with a limited moving-map showing large bodies of water, terrain outlines, and real-time aircraft position. The aircraft was also equipped with a Garmin Flight Stream 210, which allows position information from the Garmin GNS 430W to be broadcast to the flight crew’s [Electronic Flight Bags] EFBs and the ForeFlight Mobile application. While en route to the two ad hoc landing sites, TSB say that… … to prevent unwanted terrain warning…the flight crew disabled the aircraft’s [Sandel ST3400] terrain awareness and warning system (TAWS) by pulling the circuit breaker. While the Sandel ST3400… … provides a TAWS INH (inhibit) function that cancels all forward-looking terrain avoidance and premature descent alerts but does not cancel basic ground proximity warning system alerts. Given the distraction caused by having both cautions and warnings activated during off-strip landings, Twin Otter pilots at Air Tindi would disable the TAWS by pulling the circuit breaker. TSB comment that: At various times throughout the 1st leg and early in the occurrence flight (2nd leg), the flight crew identified the challenging weather conditions; however, their identification of the threat posed by the weather never reached a threshold where it was felt that they could not successfully complete the flight. At 1223, approximately 10 NM from the Lac de Gras road camp, the crew received the following weather report from the nearby Diavik mine site airfield: Winds from 300° true (T) at 25 knots, gusting to 32 knots Visibility of ½ SM in blowing snow Altimeter setting of 29.20 inHg Upon arriving over the Lac de Gras road camp, the flight crew conducted 4 approaches toward the desired landing area on the frozen lake surface, descending at times to heights below 50 feet above ground level. At the time of the 4th approach, the...
read moreAttention on Engine Shop Assembly of a S-92A CT7-8 after North Sea IFSD
Attention on Engine Shop Assembly of a S-92A GE CT7-8 after North Sea IFSD (Bristow Norway LN-OMI) On 5 June 2023, Sikorsky S-92A LN-OMI of Bristow Norway, suffered an uncommanded in flight shut down of one GE CT7-8 engine shortly after take off from the Linus jack up rig, 10 NM west of Ekofisk Lima in the Norwegian sector of the North Sea. The helicopter continued on to make a safe landing at Stavanger Airport. On 26 November 2025 the Norwegian Safety Investigation Authority (NSIA) issued their safety investigation report that focused on events during the previous engine ovehaul shop visit in Spain. The Incident Flight NSIA explain that after take off from the Linus and climbing to between 3,000 and 4,000 feet… …the crew heard a loud bang, simultaneously as the helicopter’s instruments indicated that the left engine had stopped. The…pilots went through the relevant checklists. They contacted air traffic control and issued a mayday call. After a brief round of troubleshooting, it was determined that the engine could not be restarted, and the flight would have to continue on one engine. The pilots chose to fly directly to Stavanger Airport Sola after evaluating that the helicopters performance was not sufficient to perform an emergency landing on the platform offshore. Along the way, the helicopter was met by a helicopter from the rescue service. The helicopter landed safely onshore. The Safety Investigation: Engine Examination The NSIA has carried out a brief review of the operational incident and conducted interviews with both pilots. The interviews reveals that the crew was following the company’s procedures. On initial engine inspection no visual damage to the left engine was found apart from “small pieces of metal found in the turbine area”. It was also found that the compressor was not rotating with its turbine. The left engine was sent for strip independently at a UK maintenance facility. The CT7-8 has a 5 stage axial and single stage centrifugal compressor. This is connected by an rear shaft to the gas generator turbine. At the UK facility… The engine’s cold section, hot section and turbine were dismantled. When dismantling the cold section, it was found that the joint between the centrifugal impeller and the compressor rotor rear shaft had disconnected. The impeller and rear compressor shaft have an interference fit and are normally joined by twelve T-head rotor bolts. Laboratory examination found evidence of fatigue in all 12 Inconel 718 T-bolts. Fatigue fractures had initiated at multiple locations on the individual T-bolts, with the fatigue cracks merging into a dominant crack as the fatigue propagated. All the bolts fractured, causing the rear shaft to detach from the centrifugal impeller… …and the in flight shut down. The Safety Investigation: Maintenance History NSIA report that the had been removed from another helicopter on 30 May 2020 and sent to the ITP overhaul facility in Albacete. At that time: The compressor had rubbed against the compressor casing, and the oil pressure was reported to be too high. No other significant abnormalities was reported. In 2021, the engine was test-run after repair but was rejected since the oil pressure remained too high. This was rectified. While the fault was being rectified, the engine’s original fuel control was removed (cannibalised) to be used on another engine. Another used, removed serviceable...
read moreAW189 Loss of Control – Ground, Malaysia 2023
AW189 Loss of Control – Ground, Malaysia 2023 (Leonardo AW189 9M-BOF, Fire and Rescue Department of Malaysia) On 22 July 2023 Leonardo AW189 9M-BOF of the Fire and Rescue Department of Malaysia (FRDM) suffered as Loss of Control – Ground, and rolled over at the Kuala Lumpur University Malaysian Institute of Aviation Technology (UniKL MIAT) Subang Campus in Kuala Lumpur. The 7 occupants escaped with minor injuries. The Air Accident Investigation Bureau (AAIB) of Malaysia released their safety investigation report 12 July 2024. FRDM is part of the Ministry of Housing and Local Government. They created their Fire Air Unit in 1998. Activity on the Day of the Accident The aircraft, delivered to FRDM in 2018, had been undergoing base maintenance from 24 March to 21 July 2023, when 8 ground runs were conducted. FDRM’s contracted CAAM Part 145 maintenance organisation, Galaxy Aerospace Malaysia, had requested further ground runs for Rotor Track and Balance (RTB) on 22 July 2023. Involved in these were two Pilots, one Quarter Master, one Engineer in Charge (EIC), one other Engineer, one Technician and one on-job training student. The aircraft commander (PIC) had 1820 flying hours experience (774 on type). The copilot had 1187 (1026 on type) The RTB on the ground went well and after the second ground run the EIC requested they proceed to hover checks at 7 and 70 feet. The investigators say that: While taxing to the hover test area, all of the aircraft perimeters were in normal condition until the aircraft arrived approximately 3m from the designated take-off and approach area, when the “Yaw Trim Failed” appeared on the CAS [Caution and Advisory System] message, and the co-pilot made a call out to the PIC about the situation. [T]he PIC stopped the aircraft and informed the rest of the crew that he would make some corrections to the position of the aircraft… …the aircraft suddenly spun to the left continuously and toppled. The PIC tried his best to control the spin but to no avail. After rotating for one and a half times, the helicopter rolled to the right, the main rotor blades hit the tarmac surface and stopped by itself, and the aircraft finally rested on its right-hand side. The aircraft was shutdown and everyone evacuated through the left hand side with only minor injuries. AAIB Safety Investigation Data from the Flight Data Recorder (FDR) shows that the engine start for the second ground run commenced at T = 03:40 and …at T = 03:47:40 the crew activated both the Autopilot (AP) channels and immediately deactivated the parking brakes. The investigators concluded that when the pilot applied the full right pedal during taxi the trim parameter was slightly below the minimum allowed value and this likely caused the activation of the related caution message. This was not however relevant for the subsequent event About 13 seconds after that pedal input and having completed a 90° right turn, the aircraft came to a stop. The investigators comment that the final turn that followed… …was performed by the pilot using the control technique where an initial collective input was applied to lighten the aircraft on its wheels and a subsequent pedal input in the direction of the desired rotation. Once the rotation was initiated, the pilot reduced the collective to MPOG and controlled...
read moreBo105 Loss of Control in DVE & Water Impact
Bo105 LOC-I in a Degraded Visual Environment & Water Impact (C-GGGC Canadian Coast Guard, Newfoundland 2005) On 7 December 2005, while supporting lighthouse operations, Canadian Coast Guard (CCG) MBB Bo105 C-GGGC encountered heavy snow showers and impacted the water in Mortier Bay, east of Marystown, Newfoundland. Both occupants survived the impact and egressed the helicopter but died before they were rescued. The Transportation Safety Board of Canada (TSB) issued their safety investigation report 1 November 2006. The Accident Flight The helicopter, based in St John’s, Newfoundland and operated for CCG by operated by Transport Canada (TC) Aircraft Services Directorate (ASD), was first tasked to move personnel and cargo to the Green Island lighthouse, 7 NM off Burin Peninsula. It was then to proceed to Marystown, to pick up a CCG technician and shuttle them to various Aid to Navigation (AtoNs) around the Burin Peninsula. The pilot had been flying helicopters for the CCG in Newfoundland for 27 years and had accumulated over 20,000 helicopter flying hours. He was not instrument rated and did not have a night endorsement. The pilot filed a visual flight rules (VFR) flight plan, foreseeing a completion of the flying programme “by 15:00”. The TSB report later states 17:00. The helicopter departed at 10:29. During the morning the helicopter encountered snow and made an unscheduled shutdown at a shipyard at Marystown to await better weather. There was another weather delay, this time at Winterland Airport, in the afternoon. After completing the Green Island lighthouse tasking, the helicopter arrived at Marystown at c 14:52. After collecting the technician the helicopter flew c 3NM to a small landing site at Go By Point, at the entrance to Mortier Bay. This site is on steep and rocky terrain next to an AtoN. At 15:17, the pilot reported to the flight follower at the CCG’s Marine Communications and Traffic Services (MCTS) that they had landed at Go By Point, anticipating one hour of work on site. While at Go By Point, the pilot took several photographs. Two photographs taken within 10 minutes of arrival showed sunny conditions, clear sky and unrestricted visibility. However, at 15:30, security camera at Cow Head (3.5 NM north) showed a heavy snow shower was underway. Snow was intermittent for about an hour and was light at the time of departure. The exact time of the helicopter’s departure from Go By Point is not known as now radio call was received. The helicopter did a low orbit of Duck Island, just east of Go By Point, likely assessing the landing site for a visit the next day. The helicopter then flew anti-clockwise around the shoreline of Mortier Bay as darkness approached. The helicopter would have gradually encountered heavier snowfall as it flew north. TSB explain that: Once established on a westerly heading towards Marystown, it would have been difficult to turn around when severely reduced visibility was encountered because a turn to the right would have required flight into rapidly rising terrain with a possibility of encountering whiteout conditions. A turn to the left would have placed the helicopter out over the water and caused the pilot to lose visual contact with the coast. When last observed by witnesses, the helicopter was about 1 NM east of Marystown, flying slowly at low altitude, in heavy...
read moreLoss of Control After Powerbank Jams Helicopter Collective
Loss of Control After Powerbank Jams Collective (Executive Helicopters Airbus EC155B1 EI-XHI, Shannon) On 15 September 2022, Airbus EC155B1 EI-XHI of Executive Helicopters was hover taxying on arrival at Shannon airport, when it suffered loss of control. The helicopter suffered substantial damage but no one was injured. The Irish Air Accident Investigation Unit (AAIU) issued their safety investigation report on 11 November 2025. The Accident Flight The helicopter was positioning from Kylebrack helipad to Shannon. The pilot was the sole occupant and had 12,591 hours total experience and 1,096 on type. The helicopter was flying at a ground speed of c 74 knots as it joined D1 taxiway towards the Light Aircraft Parking (LAP) area. The AAIU note that at the time… …cargo aircraft were being loaded and unloaded on the central apron and east apron areas adjacent to the LAP. On approaching the exit to the LAP area, now at c 43 knots… …the Pilot increased the helicopter’s pitch angle and then attempted to flare the helicopter in order to enter a hover. The Pilot stated that despite a number of attempts, the collective pitch lever “…would only move up one to two inches from the full down position” that it had been in during the approach to the LAP. The helicopter lost altitude and impacted the taxiway with considerable horizontal and vertical acceleration. The impact damaged the left main undercarriage, sheared the torque link of the nose landing gear and caused significant structural damage to the helicopter. Witness confirmed the impact was “nose heavy”. Impact marks on the taxiway indicate that the nose wheels impacted the ground to the left of the taxiway centreline, 31 m before the entrance to the LAP area. The impact was sufficient to activate the g-switch of the Emergency Locator Transmitter (ELT). The Multi-Purpose Flight Recorder (MPFR) also stopped recording. Its g-switch was set to 6 g. The residual forward momentum…resulted in the helicopter transiting along the taxiway towards the central and east apron areas of the airport following impact. The helicopter remained upright as it continued to travel along the ground towards ground personnel and cargo trailers that were located on the parking stand side of the ATC boundary line at Stand 24/24A in preparation for the pending arrival of an inbound cargo aircraft Seeing the approaching helicopter ground personnel wisely took what AAIU coyly call “evasive action”! The pilot struggled to slow the aircraft and was cognisant of the risk of an aircraft roll over, steering the helicopter to the left with differential braking to avoid a collision. The helicopter travelled along the taxiway and crossed the ATC boundary line adjacent to parking Stand 24/24A before it turned to the left towards the east apron area, where it came to rest. The nose landing gear torque link was found fractured. The fractured torque link had worn flat scraped along the concrete surface. There was significant structural disruption of the fuselage evident in the nose-to-cabin attachment area. The plot was sat on B/E Aerospace Fischer 230/260 H110 type / 9606 model crashworthy seat with a 5 point harness and was uninjured. The Safety Investigation Following shutdown of the helicopter, the Pilot identified that the collective pitch lever had been restricted from its full motion of travel by the portable power bank unit...
read moreAS350 HESLO Fuel Incident (Superabsorbent Polymer Contamination)
AS350 D-HEWU HESLO Fuel Incident (Superabsorbent Polymer Contamination) On 16 July 2024, Airbus AS350B2 D-HEWU, operated by Heli Transair, made a forced landing in Wiesenbach, Bavaria, while engaged in Helicopter External Sling Load Operations (HESLO). The German safety investigation body, the BFU, released their safety investigation report on 14 May 2025. The Day’s Operations The HESLO task for the day was forest liming, operated under a Part-SPO declaration for specialised operations. This involved a 25 meter line and a ‘bucket’ with a 180 kg empty mass. The 28 year old pilot, who was also the operator’s Flight Ops Manager, had c2,400 hours total, c1,325 hours on single-engine turbine helicopters (c 94 on type) and c1,300 external load flights. The pilot performed a pre-flight check that morning. This including sampling the helicopter’s main fuel tank. Approximately 10 ml of water was found during the first draining, but no water was found during the second draining. The helicopter was refuelled from a 1000 litre Ford Transit fuel bowser with 60 liters of Jet A1 fuel. The use of a mobile fuel source is very common in HESLO to maximise the underslung payload capacity. There were no issues during the first, 50 minute / 35 load, flight during which 130 litres of fuel were burnt. The helicopter was then refuelled with 160 liters of fuel. The next 40 minutes / 26 loads proceeded without incident. The BFU report that: Then, while picking up a new load—the bucket was filled with approximately 750 kg of lime—the pilot noticed that the main rotor speed dropped, but without triggering the audible low-rotor RPM warning. During cruise flight, the parameters remained normal and unremarkable. Therefore, the bucket was subsequently filled with less lime than usual, and the helicopter was flown with a lighter external load. After another 10 minutes and 5 circuits, a sudden yaw occurred while picking up a new external load. The pilot suspected a momentary loss of power and responded accordingly by reducing power and deploying a flare. Then engine power was available again, and he landed the helicopter safely on site at the loading area on a forest path. The pilot took an aircraft fuel sample and found “significant amount of contaminated fuelor a brown-colored liquid”: The tank was drained further until only clear fuel remained. The bypass indicator of the airframe fuel filter did not trigger. After consultation with the [operator’s] CAMO [Continuing Airworthiness Management Organisation] the engine was restarted and the helicopter parked on a level surface, with the assistance of the company’s maintenance manager. After a waiting period, more contaminated fuel was drained, so it was decided to completely empty the tank. Fuel was then delivered to the aircraft from “another vehicle”. There was a 190 litre uplift. After another pre-flight check, first a ground run, then a heavy hover, each lasting several minutes, were performed. Since all parameters were normal, the pilot decided to continue the forest liming operation. [The] pilot positioned the helicopter above the bucket to pick up the load [of] c600 kg of lime. [When] the bucket was about 8 meters above the ground, the helicopter yawed, the main rotor speed decreased, and the low-rotor RPM warning sounded. The pilot initiated an autorotation and headed for an area with flatter vegetation inthe forest. The helicopter landed nose-down...
read moreFirefighting K-Max Water Impact After A Close Pass by a S-64 Skycrane
Firefighting Kaman K-Max Water Impact After A Close Pass by a Sikorsky S-64 Skycrane (Precision Lift N171PL) On 22 August 2025 Kaman K-1200 K-Max N171PL of Precision Lift LLC impacted a lake near Eagle, Colorado while refilling an underslung firefighting bucket with water. The US National Transportation Safety Board (NTSB) published a rapid brief, final safety investigation report on 17 October 2025. The K-Max pilot had: 26091 hours (Total, all aircraft), 1445 hours (Total, this make and model) The pilot stated that (our emphasis added)… …there had been wind gusts throughout the day and a right quartering tailwind of approximately 15 kts was present when he was refilling the bucket. When… …another helicopter flew by his helicopter about 50-100 yds right and 150 ft above his position, he felt a push to the left. While not mentioned in the NTSB report, the accident report form reveals this was a much larger 19 t Erickson S-64 Skycrane. The NTSB remarkably does not comment on this loss of separation and the downwash risk. The K-Max pilot… …pulled back on the cyclic control, but he could not recover the helicopter, which continued pitching to the left. The K-Max descended and impacted the lake and “sustained substantial [damage] to the main rotor blades”. The pilot was able to egress the aircraft and swan to the bank, where the Helico (Helicopter Coordinator) landed and flew him to hospital for a check-up. The pilot stated there was no prior aircraft malfunction or failure. NTSB determined the probable cause to be a rather simplistic and unhelpful: The pilot’s failure to maintain helicopter control which resulted in an uncontrolled descent and impact with terrain. The NTSB make no formal safety recommendations nor do they highlight any safety messages. In contrast the pilot made the following recommendation in the accident report form: More separation of rotorcraft. I had been working one part of the fire and dipping out of this pond. The sky cranes had been working another section of the fire until they got smoked out. Air attack moved them over to the side I had been working. When the sky crane flew by it caused a downwind vortice [sic – vortex] which I could not recover from. A thorough investigation would have considered the coordination of firefighting aircraft and sought statements from other stakeholders. UPDATE 12 December 2025: In stark contrast, the Australian Transport Safety Bureau (ATSB) did just that when they issued a safety investigation report into a coordination and communication breakdown during aerial firefighting operations, near Tenterfield, New South Wales, on 31 October 2023. They wrote: …at a large fireground it is likely there will be personnel and assets from multiple organisations and jurisdictions interacting. In this scenario, non-standard procedures and practices may result in unforeseen risks emerging. It is therefore critically important for tasking agencies to take the lead, with the support of stakeholders, in developing the quality and safety standards they require for the firefighting effort to mitigate operational risks. 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: Limitations of See and Avoid: Four Die in HEMS Helicopter / PA-28 Mid Air Collision Alpine MAC ANSV Report: Ascending AS350B3 and Descending Jodel D.140E Collided Over Glacier Mid-Air Collision...
read moreH130 Sucks Out Hangar Window; Main Rotor Blade Damaged by FOD
Airbus H130 (EC130T2) Sucks Out Hangar Window; Main Rotor Blade Damaged by FOD (N3WL, Moab, UT) On 13 February 2025 privately owned Airbus H130 (EC130T2) N3WL was damaged by FOD in the hover at Canyonlands Regional Airport (CNY/KCNY), Moab, Utah. The US National Transportation Safety Board (NTSB) rapidly released a short final report on 9 May 2025. The pilot told the NTSB that shortly lifting into the hover, a window dislodged from a nearby hangar door and impacted a main rotor blade from behind. The pilot initiated an emergency landing, landing hard, but without injuries to the 7 occupants. Although the image below seems to indicate damage to the skids, no such damage is reported by NTSB. The pilot made two suggested safety recommendations to prevent a reoccurrence: A more detailed inspection of the hangar Departing from a position further away from the hangar 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: Fire Extinguisher Cover Fenestron FOD FOD and an AS350B3 Accident Landing on a Yacht in Bergen Air Ambulance Helicopter Downed by Fencing FOD Pedestrian Seriously Injured by Air Ambulance Landing at Melbourne Hospital HEMS Downwash Injuries: Two More Case Studies Tool Bag Takes Out Tail Rotor: Fatal AS350B2 Accident, Tweed, ON Loose Clothing Downs Marijuana Survey Helicopter When Habits Kill – Canadian MD500 Accident EC120 Forgotten Walkaround Fenestron Failure EC130B4 Hawaii Business Jet Apron Jet Blast Injury BP has shared a video on the threat of downwash (albeit with larger helicopters). Aerossurance has extensive air safety, flight operations, airworthiness, human factors, helideck, aviation regulation and safety analysis experience. For practical aviation advice you can trust, contact us at: enquiries@aerossurance.com Follow us on LinkedIn, Blue Sky @aerossurance.bsky.social and Twitter @Aerossurance for our latest...
read moreA Screw in the Wrong Place…A Loss of Hoist Cable
A Screw in the Wrong Place…A Loss of Hoist Cable (Honda Airways AW139 JA03FD Breeze-Eastern Hoist) On 17 February 2024, Leonardo AW139 JA03FD of Honda Airways, operated for the Saitama Disaster Prevention Air Squadron, inadvertently released the hoist cable and test load during a post-maintenance hoist check at Honda Airport, Kawajima. The Japan Transport Safety Board (JTSB) issued their safety investigation report on 25 May 2025. The Serious Incident Flight The helicopter’s hoist cable had been replaced and so a post-maintenance check flight was necessary. On board were two pilots, an Air Squadron Officer (ASO – the hoist operator) and a mechanic (‘Mechanic A’, acting as a hoist instructor). The JTSB explain: The load test required after cable replacement, confirms each function of hoist operates normally with maximum hoist load, 600lb (about 272 kg). In this case, the cable had been replaced the day before by Mechanic B and C, and it was planned to conduct load test, with 136 kg…and [then] 272 kg….on the hook at the end of the cable. This would be achieved using two and then four 68 kg weights. At about 10:17, for the first load test, the helicopter reeled out the cable to the ground at a hovering height of about 50 ft, and ground crew hooked a 136 kg weight. The helicopter then climbed to hovering altitude of about 340 ft, the Air Squadron Officer began to reel out cable to the maximum length (about 300 ft), which was for Mechanic A to confirm that it would automatically stop at the maximum length. As the cable reached its maximum extension “the weight fell to the ground along with the cable” near Taxiway E4. There were no injuries or damage. The helicopter had an electrically operated Breeze-Eastern hoist: The cable is 307 ft (about 93.5 m) long, has a diameter of 4.75 mm, and is wrapped on an aluminum drum. The cable is inserted in the slot of drum and fixed by tightening the screw against the cable strand. As the end of the cable is welded to prevent fraying, the screw must contact the cable strand and not the welded end. The hoist is fitted with limit switches which automatically stop the drum when remaining cable gets to 3.5 to 4.5 wraps. Unacceptable ‘bird caging‘ damage had been found on the previous cable fitted to the hoist so on 15 February 2024 ‘Mechanic B’ (a licenced engineer) began to unwind the old cable using the thumb wheel on the hoist pendant. Mechanic B stopped unwinding when the full-out limit switch actuated and the drum stopped, confirmed that the number of cable wrap which was 4 remaining on the drum and took a photo with his smartphone. And then, Mechanic B removed the screw which fixed the cable end…to pull out the old cable from the slot on the drum and completed the day. The AW139 Aircraft Maintenance Manual (AMM) however required the limit switch be overridden and the cable fully paid out. The AMM also discusses this screw, saying: Make sure that the screw engages sufficiently the cable end to safety the cable correctly into the drum shoulder. To do this, you can see only a small part of the cable white mark that goes out of cable housing in the drum shoulder...
read moreCold Comfort Conference Call: USAF F-35A Alaska Accident
Cold Comfort Conference Call: USAF F-35A Alaska Accident On 28 January 2025 US Air Force Lockheed Martin F-35A 19-5535 of the 355th Fighter Squadron crashed and was destroyed at Eielson Air Force Base (AFB), Alaska (a total loss valued at $196.5 mn). The pilot ejected and suffered only minor injuries. The USAF released their Accident Investigation Board (AIB) report on 26 August 2025. A USAF AIB does not conduct a safety investigation (a separate Safety Investigation Board [SIB] is convened but their report is not released publicly), instead (our emphasis added): In accordance with AFI 51-307, Aerospace and Ground Accident Investigations, this accident investigation board conducted a legal investigation to inquire into all the facts and circumstances surrounding this Air Force aerospace accident, prepare a publicly-releasable report, and obtain and preserve all available evidence for use in litigation, claims, disciplinary action, and adverse administrative action. The Accident Flight A Landing Gear Fault After Take Off The accident aircraft was number 3 of a flight of four 355 FS F-35As, callsign YETI, that was to conduct an Air Combat Maneuvers (ACM) sortie with two other F-35As, callsign CHEVY. The 355 FS is part of the 354th Fighter Wing (354 FW). The pilot of YETI 3 was a current F-35A evaluator and instructor pilot with 2702 hours in total (555 hours on type). Shortly after takeoff, the pilot of YETI 3 received an OVERSPEED GEAR caution. They identified that instrumentation showed yellow and black hash marks for the Nose Landing Gear (NLG) that indicated ‘gear in-transit’. Their wingman reported the NLG door was “open by about 2 inches”. The pilot followed the necessary checklists, which included lowering the gear and conducting flight control system resets. The NLG was initially angles c25 degrees left. This was reduced to c17 degrees during this fault finding. Calling a ‘Conference Hotel’: Fault Finding Technical Support Call with Lockheed Martin The pilot then requested a ‘Conference Hotel’, namely a conference call with Lockheed Martin engineers. This was swiftly organised through the on-duty Supervisor of Flying (SOF) at Eielson AFB. Although the AIB don’t say when this call was requested it appears to have been set up in less than 20 minutes. On the call were the Eielson SOF, a “senior 354 Operations Group (354 OG) leader” and 5 Lockheed Martin engineers (a senior software engineer, a flight safety engineer and three landing gear systems engineers). The Eielson SOF was in turn in contact with the pilot. According to the AIB report the engineers… …requested information on, among other things, how much fuel the MA [Mishap Aircraft] had remaining, direction of the NLG wheel, and health reporting codes [HRCs]. The AIB then says that they… …did not request or receive information about where the mishap was occurring and ambient air temperature. That’s an odd observation because presumably they did know the call was arranged by the Eielson SOF, that Eielson AFB is in Alaska and that in January Alaska is rather chilly…! Initially an arrestor landing was mooted, but the pilot pointed out that “cable arrestment must be in a 3-point attitude” according to the published procedures, meaning the NLG would have to be on the ground prior to the cable engagement. That course of action was abandoned because of the concern that an uncentered nose wheel could...
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