AW139 Loss of Control Climbing Away from SAR Exercise
AW139 LOC-I Climbing Away from SAR Exercise (Esso Australia Leonardo AW139 VH-EXK) On 2 October 2024 Esso Australia Leonardo AW139 VH-EXK was conducting Search and Rescue (SAR) training under Visual Flight Rules (VFR), just off the coast of Golden Beach, Victoria, when it suffered a Loss of Control – In Flight (LOC-I). The Australian Transport Safety Bureau (ATSB) issued their safety investigation report on 20 May 2025. The Incident Flight The helicopter departed Longford Heliport, Victoria, adjacent to the Esso Longford gas plants, at 0816 local time for a SAR exercise. The crew consisted of the Aircraft Commander (15,402 total hours, 2,603 on type), a Flight Instructor (11,129 total hours, 3,695 on type), a Check Aircrewman, and a Hoist Operator. Esso Australia provide daytime SAR coverage in support of their Bass strait gas production. The ATSB state that on 11 June 2024, was Esso Australia issued with an CASA air operator’s certificate (AOC) and a Part 138 aerial work certificate (for SAR operations). While Esso Australia had previously operated in the private category, for at least 5 years they had operated under an AOC. ATSB say the Aircraft Commander was initially Pilot Flying (PF) and the Instructor Pilot Monitoring (PM) and that the exercise took place c 2 km offshore and… …involved retrieving a training aid amidst large swells, sea spray and encroaching fog from the north-west. The instructor estimated that the fog bank was less than one kilometre from shore at the time. However, clear skies were visible to the north and north‑east… The training aid was deployed, and the exercise commenced at about 0825. As the training progressed, the helicopter’s proximity to the fog on the left side, where the instructor was seated, was observed to be decreasing. The flight crew noted that the skies were clear to the north and northeast of their position on the instructor’s side of the helicopter. After conducting training for approximately 40 minutes, the instructor assumed control as PF and the check aircrewman assumed the role of hoist operator to retrieve the training aid. This involved hovering approximately 40 ft above the sea. Their attempt was unsuccessful however. Due to “encroaching fog” the instructor elected to depart and announced they would climb to avoid fog. At 0908, the instructor manoeuvred the helicopter onto a north-westerly heading… …and engaged the radar height hold (RHT) system while climbing using a combination of the collective beep trim and force trim release (FTR). At this time, the captain, acting as the PM, was focused on marking the GPS position of the training aid. This was to facilitate its recovery in another exercise later that day. At about this time, the helicopter inadvertently entered instrument meteorological conditions (IMC), and the instructor announced their intention to move forward to depart. The right cabin door was open and approximately 40 ft of the hoist cable was extended. The check aircrewman objected via the intercom to departing with the hoist still extended, as the post‑hoist procedures requiring the aircrew to secure the hoist cable and cabin had not yet been completed. Despite this objection, the instructor proceeded with the departure with the intention of reentering visual meteorological conditions (VMC). The instructor accelerated and continued to climb, reaching an altitude of 185 ft and an airspeed of 72 kt before beginning a shallow...
read moreAir India B787 GEnx-1B In Flight Shut Down After Maintenance Error 5 Years Earlier
Air India B787 GEnx-1B In Flight Shut Down After Maintenance Error 5 Years Earlier (VT-ANW) On 4 August 2023 Air India Boeing 787-8 VT-ANW suffered un-commanded In Flight Shut Down (IFSD) of its No 1 GE GEnx-1B engine 9 minutes after take off, forcing a return to Mumbai Airport. The Indian Aircraft Accident Investigation Bureau (AAIB) published their safety investigation report in May 2025. This was the source of the illustrations below. Note: This article was prepared a week a go but publication was delayed as AAIB published their Preliminary Report on 11 July 2025 on the unrelated fatal accident involving Air India 787-8 VT-ANB at Ahmedabad on 12 June 2025. The Safety Investigation A post-incident engine strip released the release of an High Pressure Compressor (HPC) Stage 10 blade was the cause of the IFSD and Electronic Engine Control (EEC) auto-restart attempts were unsuccessful due to distress from the blade’s release. There are two locking lugs for each HPC stage. These secure the blades in a circumferential fashion to prevent blade release from the load slot. During installation a set screw is torqued, raising the locking lug into the locking slot in the spool, but this depends on the correct positioning of the lug in the slot. Investigation found that “the LH locking lug was installed out of the lock slot and the RH locking lug was installed partially inside the lock slot”. This improper installation caused the release of the blade. The last maintenance action on the HPC stage 10 blades had occurred at the GE EvergreenEngine Services (GEEVES) facility in Taiwan in 2018. Unfortunately, but perhaps understandably due to the time having passed, the Indian AAIB report goes no further to understand the circumstances of the 2018 maintenance and the human factors that may have affected the maintenance. Safety Resources You may also find these Aerossurance articles of interest: B787 GEnx Fan Shaft Failure (Air India 2012) Uncontained PW1524G Failure During CS100 Certification Testing Machining Defect Cause of V2500 Failure Power of Prediction: Foresight and Flocking Birds NTSB Recommendations on JT15D Failure to Meet Certification Bird Strike Requirements CFM56-7 HPC Titanium Fire Due to VSV Maintenance Assembly Error (United Boeing 737-924) B767 Fire and Uncommanded Evacuation After Lockwire Omitted Japanese Jetstar Boeing 787 GEnx-1B Engine Biocide Serious Incident 17 Year Old FOD and a TA-4K Ejection NDI Process Failures Preceded B777 PW4077 Engine FBO T-Bolt Trouble: Unrecorded Maintenance on US HEMS BK117C2/H145 and Loss of TR Pitch Control Fatal $16 Million Maintenance Errors CHC Sikorsky S-92A Seat Slide Surprise(s) Loose B-Nut: Accident During Helicopter Maintenance Check Flight USAF RC-135V Rivet Joint Oxygen Fire The Missing Igniters: Fatigue & Management of Change Shortcomings B1900D Emergency Landing: Maintenance Standards & Practices Crossed Cables: Colgan Air B1900D N240CJ Maintenance Error Engine Maintenance Introduced FOD that Caused an EC120 Power Loss SAR AS365N3 Flying Control Disconnect: BFU Investigation Engine & Emergency Flotation Failures – Greenland B206L4 Ditching Flying Control FOD: Screwdriver Found in C208 Controls Lost Tool FODs Propeller Blade, Penetrating Turboprop’s Fuselage Dash 8 Q400 Return to Base After Pitot System Contaminated By Unapproved Test Kit Lubricant Dash 8 Q400 Control Anomalies: 1 Worn Cable and 1 Mystery We have written several general articles related to maintenance safety: Professor James Reason’s 12 Principles of Error Management How To...
read moreBrazilian Helideck Rollover After Precautionary Landing
Brazilian Helideck Rollover After Precautionary Landing (Delta Aero Taxi Airbus AS350B on YM OPUS) On 9 June 2022 Airbus AS350B PT-HMD of Delta Aero Taxi rolled over on the helideck of bulk carrier YM OPUS in the Bay of São Marcos, Brazil after making a precautionary landing. The Brazilian accident investigation agency CENPIA published their safety investigation report on 2 June 2025. The Accident Flight The pilot (2600 total hours but only 17:25 on type) was returning onshore after dropping passengers on the bulk carrier SM GEMINI 2. The passengers had disembarked with the rotors running and a passenger had closed the helicopter door. Shortly after the pilot reported “hearing an abnormal noise and experiencing unusual aircraft vibration”. He reduced speed to c 60 knots “but the phenomena persisted”. Upon inspecting the aircraft interior during flight, he noticed that the left door was notclosed appropriately. This led him to suspect that the noise originated from a seat belt buckle striking the fuselage. The pilot decided to perform a precautionary landing the YM OPUS. Upon landing the pilot reportedly “locked the controls” and while rotors running intended to step out and check the door. Though prohibited by the Brazilian Code of Aeronautics, disembarking while rotors running was described as “habitual” in that operator. At that moment, the helicopter tipped over while he was still inside the cabin. The pilot suffered minor injuries. Safety Investigation External dents support the pilot’s hypotheses of a seat belt stuck outside the door. However: …photographic evidence from the accident site showed that the position of the collective pitch control was fully up, indicating that it had not been locked. The cyclic control, on the other hand, had its friction fully tightened. CENIPA found the operator did not have specific training for operating from offshore helidecks and that offshore operations were not part of their approved Operations Specifications. CENIPA note that: Airbus Helicopters’ Safety Information Notice (SIN) nº 3268-S-00 warned about incidents in which helicopters inadvertently lifted off due to collective pitch movement without pilot input. The notice concluded that failure to lock the collective after landing was a contributing factor in such events. 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: Be Careful If You Step Outside!: Unoccupied Rotors Running AS350 Takes Off AS350B3 Rolls Over: Pilot Caught Out By Engine Control Differences 29 Seconds to Impact: A Fatal Night Offshore Approach in the Irish Sea CHC Sikorsky S-92A Seat Slide Surprise(s) Marine Pilot Transfer Winching Accident: referenced in the Royal College of Art (RCA) & Lloyd’s Register Foundation Safety Grand Challenge: Safe Ship Boarding & Thames Safest River 2030 Engine & Emergency Flotation Failures – Greenland B206L4 Ditching North Sea Helicopter Struck Sea After LOC-I on Approach During Night Shuttling Loss of Sikorsky S-76C+ 5N-BQG of Eastwind Off Nigeria 24 October 2024 South Korean Night Black Hole Spatial Disorientation Fatal Helicopter Accident Loss of Control, Twice, by Offshore Helicopter off Nova Scotia Offshore Night Near Miss: Marine Pilot Transfer Unintended Descent AAIB Report on 2013 Sumburgh Helicopter Accident Fatal Offshore S-76C++ LOC-I & Water Impact Brazil 2022: CENIPA Investigation SAR Helicopter Loss of Control at Night: ATSB Report NTSB Investigation into AW139 Bahamas Night Take Off Accident Night Offshore Training AS365N3 Accident in India...
read moreB214ST Tail Rotor Drive Shaft Coupling Misassembly
B214ST Tail Rotor Drive Shaft Coupling Misassembly (C-GDYZ, HTS) On 7 June 2021 Bell 214ST C-GDYZ of Helicopter Transport Services (HTS) made a forced landing 14 nm NE of Nipigon, Ontario while returning from a firefighting tasking. The pilot was seriously injured. Transportation Safety Board of Canada (TSB) released their safety investigation report on 8 February 2022. The Accident Flight The helicopter was being flown by a single pilot (8400 hours total time, 1940 on type). The aircraft was equipped with a 550-gallon collapsible water bucket on a 150-foot long line. The pilot conducted approximately 45 drops before informing the fire boss on board the bird dog/spotter aircraft that the helicopter was low on fuel and that the end of his duty day was nearing. The return trip…to the Nipigon fire base was flown at 3000 feet above sea level, about 1600 feet above ground level. The helicopter was travelling at 70 to 74 knots in a nose-down attitude of roughly 7° due to the empty water bucket when the pilot was alerted by a vibration in the tail rotor pedals and a grinding noise. Moments later, the 42° BOX OIL PRESS and 90° BOX OIL PRESS annunciators for the 2 tail rotor gearboxes illuminated, and there was an audible engine overspeed noise. The helicopter yawed to the right and the nose began to pitch down. The pilot lowered the collective control and moved the cyclic control aft to counteract the nose-down tendency, increase the main rotor rpm, and enter autorotative flight. As the helicopter began to spin, the pilot released the long line and water bucket by kicking the manual cargo release pedal. The pilot transmitted a Mayday call stating that he had lost tail rotor control. While the helicopter was descending at approximately 1000 to 1500 fpm, the pilot made 3 attempts to use some engine power to fly the helicopter to a suitable landing area near a small lake. He was able to regain some control over the adverse yaw via airflow acting on the vertical stabilizer. As the helicopter descended below treetop height, he raised the collective control to cushion the landing, at which point the low rotor rpm horn activated. At 1924, the helicopter landed on its left skid gear with almost no forward speed…and came to rest leaning to the left on soft, boggy terrain. Both pilot seats were equipped with a shoulder harness, but the occurrence pilot felt that it restricted his ability to use the vertical reference bubble window. Therefore, the pilot did not utilize the shoulder harness during long line or slinging operations. The TSB Safety Investigation Investigators identified the tail rotor was not rotating at the time of impact, indicating a loss of tail rotor drive. The Bell Model 214ST Rotorcraft Flight Manual states: A failure of this type, in powered flight, will result in the nose of the helicopter swinging to the right (left side slip) and usually a roll of the fuselage. Nose down tucking will also be present. The severity of the ships [sic] initial reaction will be affected by airspeed, cabin-loading, center of gravity, power being used, and density altitude. TSB comment that: On the occurrence flight, at approximately 1600 feet above ground level, the pilot completed [the Flight Manual] actions when he recognized the loss...
read moreEC155 / Light Aircraft Mid Air Collision: All Survive
EC155 / Light Aircraft Mid Air Collision: All Survive (Airbus EC155B1 F-HEGT of Héli Sécurité and Nord 1203 III F-AYVV) On 8 February 2024 Airbus EC155B1 F-HEGT of Héli Sécurité and vintage single engine piston Nord 1203 III F-AYVV collided in mid air over Montmélian, Savoie. Both aircraft were damaged, but remained controllable. Their pilots managed to land, in a field for the helicopter and at Albertville aerodrome for the aeroplane. Le Bureau d’enquêtes et d’analyses pour la sécurité de l’aviation civile (BEA) issued their safety investigation report in December 2024. The Accident Flights The dark blue helicopter, flown by a single pilot (3000 hours total time) accompanied by a ‘safety pilot’ (400 hours), was transporting six passengers from Chambéry airport to the Courchevel mountain airfield. The aeroplane (white with red wing tips and propeller hub) was making a local post-maintenance check flight with a pilot (23,000 hours total time) accompanied by a mechanic to record engine parameters. The 1957 built aircraft was not equipped with, nor was it required to have, a transponder. Both aircraft were operating under Visual Flight Rules (VFR) in Class G uncontrolled airspace and were on converging flight paths in the Albertville valley at the, same altitude with a closing speed of c 280 kt. The helicopter crew described good visibility but heavy cloud cover. Despite both pilots monitoring the same radio frequency, neither was aware of the other’s presence until moments before the collision. The BEA recount: At 11:45:53, the two pilots on board the helicopter perceived F-AYVV coming towards them, at the same altitude. The pilot flying sharply turned right while pitching down while the aeroplane continued in a straight line. The aeroplane pilot who saw the helicopter at the last moment, did not have the time to carry out an evasive action. At 11:45:55, the tips of the helicopter’s [12.6 m diameter] main rotor blades came into contact with the aeroplane’s left fairing and made a cut in the root of the left wing, between the leading edge and the main spar (see Figure 1, point ❶). The helicopter pilot started an emergency descent, reducing the speed to 80 kt. While searching for an obstacle-free area for landing, he transmitted a distress message by radio and activated the emergency locator transmitter. He landed in a field less than three minutes later (point ❷). The helicopter’s landing gear sank into soft ground by c 10 cm. The damage was limited to the tips of two of the five main rotor blades, a notch on the trailing edge of one blade and blade rubbing marks the fenestron fairing that probably occurred during the landing. After checking the controllability, the Nord [pilot initiated a descent, returning to Albertville aerodrome, landing five minutes later. Cuts were found cut on the left-hand side of the engine cowling and the left-hand wing leading edge down to the spar. The left-hand wing fuel tank was torn and the he left-hand aileron control rod was severed. BEA Analysis The collision took place in Class G uncontrolled airspace, not covered by a Flight Information Service (FIS), in a mountainous area. In this class of airspace, neither a transponder or radio calls are mandatory. Maintaining separation is based on the ‘see and avoid‘ principle. See and avoid relies on flight crew monitoring...
read moreCHC Sikorsky S-92A Seat Slide Surprise(s)
CHC Sikorsky S-92A Seat Slide Surprise(s): (LN-OQE 2010 and LN-OQG 2013) On 1 April 2010, at 500 ft on approach to an offshore installation, the Aircraft Commander of Sikorsky S-92A LN-OQE of CHC Helikopter Service found his seat had become detached. The Accident Investigation Board Norway (AIBN), now the Norwegian Safety Investigation Authority (NSIA), published their safety investigation report, in Norwegian only, on 15 April 2015 (a disappointingly excessive 5 year and one similar incident later). The Incident Flight The helicopter was being flown by the Co-Pilot as ‘Pilot Flying‘. Just before reviewing the Pre-Landing Checklist for landing on the Gullfaks B offshore installation, the Aircraft Commander, the ‘Pilot Monitoring‘, was adjusting his seat to the forward position for landing when it came loose from its mounting rails. He grabbed the grab handles in the ceiling [believed to be the handhold above the windscreen] and then had to hold on to them to prevent the seat from falling off the rails with the consequent risk that the control sticks (collective and cyclic) could be blocked or pinched. The Aircraft Commander told the Co-Pilot he could not let go and made it clear the Pilot Flying “was now on his own with regard to the maneuvering”. The Co-Pilot was able to make an uneventful landing on Gullfaks B without further problems. A week later CHC issued “Information to Crew (ITC) 80 – 07.05.2010” that stated that the incident involved a potential for the flight controls to be blocked. The company noted that the incident ended well because the crew remained calm in a difficult situation. The Co-Pilot informed the AIBN that… …the weather was as good as it could be in the North Sea, and that the approach was otherwise unproblematic and obstacle-free After landing offshore the pilots attempted to refit the commander’s seat onto its mounting rails (presumably to certify under an Aircraft Commanders’ Part-145 145.A.30(j) authorisation). However, they discovered that the forward slide stop was missing. Significantly, they also found the co-pilot’s seat was missing its rear slide stop. Safety Investigation LN-OQE had been in for a maintenance check less than a week before. A Nose Landing Gear(NLG) Hinge Inspection had been performed, which necessitated removal of the pilots’ seats. On these Martin-Baker High Comfort Crew Seats both the locking brackets (slide stop, P/N MBCS13711) and locking pins (quick release pin) must be attached to the mounting rails after the seats have been put in place. After performing the NLG Hinge Inspection, the seats were reinstalled, but: the locking brackets for both were omitted on the commander’s seat the front and rear locking pins were omitted on the co-pilot’s the rear locking pin was missing (though the front pin was fitted) There is no comment on where the omitted items were. Two days after the incident, CHC issued Maintenance Alert Notice TI-016, requiring inspection of the pilot seats in all of the company’s S-92 helicopters before the next flight to ensure that locking pins and locking brackets were installed. No similar defects were found on any of the other helicopters. However, one helicopter was missing a slide stop, but here the locking bolts were in place so that, according to CHC, the seat could not have come off the rails. In its internal investigation, CHC identified several factors that contributed to...
read moreAW109SP Helicopter Air Ambulance Mountain Landing Accident Utah
AW109SP Helicopter Air Ambulance Mountain Landing Accident Utah (Intermountain Life Flight N631HC) On 8 October 2024, Leonardo AW109SP GrandNew N631HC, a helicopter air ambulance of Intermountain Life Flight, landed hard during a night call out to attend a patient at >10,000 ft amsl in a mountainous region of Utah. The landing gear collapsed and the belly was damaged. One of the three occupants suffered a minor injury. The US National Transportation Safety Board (NTSB) issued a sparse safety investigation report on 8 April 2025. The report is mostly based on the pilot’s detailed statement. The Accident At about 03:30 the pilot, who was going to operate the aircraft single pilot, was called by Comm-Center (CC) asking if he would accept a flight into the High Uintahs wilderness area “for a patient in the woods”, noting that the Summit SAR team, a ground SAR team was still to reach the casualty. The pilot was told that another operator, AirMed “had turned this flight down due to smoke and visibility” and the Department of Public Safety (DPS) “did not want to respond at this time”. This appears to be case of helicopter shopping where the tasking agency calls several operators. A positive is that the pilot was told others had declined, providing context to inform their decision making and encourage critical thinking The downside is this can put pressure on the pilot as they may perceive they are the ‘last hope’ for a casualty until dawn. The pilot, who had 5127 hours total time, 1105 hours at night and 170 on type, reported that: Conditions were some clouds in the sky, Zero moon illumination as the moon had set at approximately 2207hrs. After receiving the initial details he examined ForeFlight, and… …looked at fuel requirements and not knowing if I would need to search for their location elected to add fuel to ensure I had a loiter time if needed. I knew that minimum fuel to complete the flight from the scene area to IMED in Murray, Utah was 150kg which included my reserve. The crew went to the aircraft, and the pilot completed a pre-flight risk assessment selecting: Night Shift Flight between 2-6 am Unfamiliar destination Technical flight The first three are self evident but its unclear what the last relates to. I added my fuel and added more than I had planned by mistake (due to I’ve never topped off the aircraft at Logan and when at IMED it is usually 410 when fuel is about to spill out the fuel port). Prudently the pilot… …mentioned to the crew about the possibility of reduced visibility and that we would take it slow with that consideration and then we departed. Enroute to the destination it was brought up in discussion why we were being called and I mentioned that Airmed had turned down for visibility (thought I had mentioned that before), DPS said that they would wait till sunrise. The next comment in the pilot’s statement indicates that by this point of the flight the crew no longer expected to search for the casualty, presumably because the ground SAR party had now reached them and passed a landing site location. It was mentioned that the altitude of the LZ was approximately at 9300’. I noted the temperature @ 11º since we...
read moreT-Bolt Trouble: Unrecorded Maintenance on US HEMS BK117C2/H145 and Loss of TR Pitch Control
T-Bolt Trouble: Unrecorded Maintenance on US HEMS BK117C2/H145 and Loss of Tail Rotor Pitch Control (Metro Aviation N191LL) On 6 March 2024 Metro Aviation Airbus BK117C2 / H145 helicopter air ambulance N191LL was damaged at Purdue University Airport (LAF), West Lafayette, Indiana. The three occupants were uninjured. On 24 April 2025 the US National Transportation Safety Board (NTSB) released their safety investigation report, in a creditable 14 months. The Accident Flight The pilot reported that, while in a hover taxi to accelerate for takeoff, he felt a force against his feet from the pedals. The helicopter yawed to the right, so he applied full left pedal, but when the pedal was depressed, there was no resistance and no effect on the helicopter’s yaw. The helicopter landed hard came to rest and rest upright, with damage to “the fuselage, tailboom, vertical fin, horizontal stabilizer, tail rotor assembly, and one main rotor blade”. The Safety Investigation – The Accident Sequence The T-bolt and its attachment bolts, which connect the pitch change bellcrank to the pitch change slider was found to have become disconnected. Investigators concluded that the T-bolt attachment bolts had been installed but not torqued and lock wired, allowing them to back out while rotors running. Once the attachment bolts backed out, the T-bolt also backed out resulting in a loss of tail rotor pitch control. The T-bolt then likely impacted and damaged a tail rotor blade. The subsequent imbalance led to the overload separation of the upper vertical fin. One attachment bolt was found on the ramp after the accident, and the other was “lodged into a honeycomb panel at the aft-lower area of the fuselage, adjacent to the fuel cell.” The Safety Investigation – The Maintenance History During maintenance a few days prior, the T-bolt and its attachment bolts were removed by a mechanic at the direction of a lead mechanic to facilitate troubleshooting of adjacent components for the tail rotor control system. As the T-bolt’s removal was temporary and quick, the mechanic crucially choose not to record the removal in the Work Order’s Discrepancy Sheet. The T-bolt attachment bolts were then subsequently temporarily installed “finger-tight’ by a second mechanic to assist a third mechanic who was installing the tail rotor blade mounting forks and pitch change links. According to the NTSB “the first mechanic [sic] was tasked to another company helicopter shortly after”. The NTSB state that “while he stated he relayed to the other mechanics that the T-bolt attachment bolts were finger-tight, no one followed up on the installation of the T-bolt attachment bolts”. This part of the NTSB report is rather ambiguous but it seems likely the NTSB mean the mechanic tasked to another job was the second mechanic, who reinstalled the bolts finger tight, rather than the first mechanic who did the unrecorded removal. Without a maintenance discrepancy entry for the removal of the T-bolt, there was no open task to verify T-bolt installation was complete. Furthermore, no one identified that lock wire was missing from these bolts during the final checks before the helicopter was released to service. NTSB Probable Cause The failure of maintenance personnel to properly install the tail rotor pitch change slider attachment hardware (T-bolt), which led to the disconnection of the pitch change slider, a loss of tail rotor control, and subsequent...
read moreThree Fatalities When US Air Ambulance Helicopter Struck Goose at Night
Three Fatalities When US Air Ambulance Helicopter Struck Goose at Night (Air Evac B206L3+ N295AE) On 20 January 2024, at 23:23 Local Time, Bell 206L3+ air ambulance N295AE of Air Evac Lifeteam was destroyed in an accident near Hydro, Oklahoma. The three occupants, the pilot, flight nurse, and flight paramedic were all fatally injured. The US National Transportation Safety Board (NTSB) stated in their safety investigation report, issued on 19 March 2025, that having dropped off a patient at the Mercy Health Center Heliport, Oklahoma City, Oklahoma: The helicopter was en route back to the crew’s home airfield [Weatherford, Oklahoma] when it encountered a flock of geese during the night flight. The helicopter was in cruise flight about 500-600 ft above ground level and at 110 knots groundspeed when the encounter occurred. The bird strike resulted in an inflight breakup of the helicopter and subsequent impact with terrain. The debris field was about 265 yards long and 455 yards wide. Bird remains were recovered from the area of the cockpit, tail rotor and pitch links. Samples were sent to the Smithsonian Institution’s Feather Identification Laboratory. These were identified as cackling goose (Branta hutchinsii), which until 2004 was treated as a subset of the canada goose family (at which time the four smallest sub-species were reclassified). DNA testing confirmed the remains were consistent with female cackling geese, which have an average mass of 2 kg. At least two birds were involved (as three feet were found within the debris). Following the accident, the operator revised their General Operational Manual and pre flight risk assessment form: They encouraged all pilots to review bird migration tracking websites before flight, increased the recommended cruise altitude to 2,500 ft above ground level in areas of potential bird activity, and moved the recommended approach to land/descent airspeed to around 80-90 knots versus descending at cruise airspeed. Interestingly, despite encouraging use of bird migration data, NTSB also reported that: Preflight mission planning for the flight would likely not have detected a risk for a bird strike. A review of military and civilian bird hazard websites showed that at the time of the accident, the probability of bird strike in that area was deemed to be low. In addition, historic migration data also estimated the probability of a bird strike at the time of the accident as low. Our Safety Observations The actions taken after the accident all appear to be foreseeable safety improvements that have been foreshadowed by prior bird strike accidents. NTSB do however note that to the operator’s credit the helicopter had been modified via a Supplemental Type Certificate to replace the pilot-side windshield with a polycarbonate kit “that offered increased resistance to windshield penetration by a bird strike”. The specific product is not identified but an example can be found here. NTSB do not comment further but the STC windscreens would be unlikely to be cleared for a 2 kg bird like a female crackling goose as even FAR 29.631 for the windscreens of larger rotorcraft is only a 1 kg test requirement. Safety Resources On 3 October 2023, the FAA released Special Airworthiness Information Bulletin (SAIB) AIR-21-17R1 Rotorcraft Bird Strike Protection and Mitigation, to inform pilots about the risk of bird strikes. The European Safety Promotion Network Rotorcraft (ESPN-R) has a helicopter safety discussion...
read moreEngine & Emergency Flotation Failures – Greenland B206L4 Ditching
Engine & Emergency Flotation Failures – Greenland B206L4 Ditching (Sermeq Helicopters OY-HIO) On 28 February 2024 Bell 206L4 OY-HIO Sermeq Helicopters ditched in Tunulliarfik Fjord (the inner section of Skovfjord) near Qaqortoq in southern Greenland. Although the Emergency Flotation System (EFS) was activated, it malfunctioned and the helicopter rolled over. The pilot, the sole occupant, escaped unharmed. Greenland is an autonomous territory within the Kingdom of Denmark and so the Accident Investigation Board (AIB) Denmark (Danish: Havarikommissionen for Civil Luftfart og Jernbane or HCLJ) investigated this accident. They released their safety investigation report on 5 March 2025. The Accident Flight Th helicopter was making a VFR positioning flight from Narsarsuaq (BGBW) to Qaqortoq (BGJH) cruising at 1500 ft when… …the engine chip detector light illuminated on the caution and warning panel, and a few seconds later, the engine low oil pressure light started illuminating. Engine oil pressure indicated zero and indicated oil temperature decreased. Moments after: The N1 (Gas Producer Turbine rotations per minute) indication was zero, and both the engine-out warning light and horn activated. However, the engine still produced power with a normal N2 (Power Turbine rotations per minute) indication. Consequently the pilot selected a narrow sand bar alongside the steep southern cliffs of the fjord and initiated a powered descent. The engine however stopped and the pilot was forced to complete an autorotation, activating the EFS. The helicopter ditched a few meters from the sand bar. While the rotors were still turning the helicopter started slowly rolling onto its left hand side in a water depth of approximately 0.5 m. The helicopter’s fixed Emergency Locator Transmitter (ELT) was mounted just below the instrument panel and fortuitously remained above the waterline. It activated automatically, tiggering the tasking of a Search and Rescue (SAR) helicopter by Joint Arctic Command. At 17:17 an Air Greenland H225 SAR helicopter arrived on scene and located the accident site at 17:29. The pilot, who was wearing “ordinary clothing” and whose legs had gotten wet was found conscious but with a low body temperature, having sat outside in -5 °C for c75 minutes. He was kept in hospital overnight. Safety Investigation – Survivability The investigators note that the SAR operation was “effective and positively impacted the chance of survival in a hostile area”. Though not legally required, in the opinion of the AIB, a survival suit in a hostile area would most likely have reduced the risk of hypothermia. Safety Investigation – Engine Following examination of the Rolls-Royce 250C30 engine the investigators concluded that the engine power loss was due to the following sequence of events: The bearing no. 8 thrust plate anti-rotation tab separated from the thrust plate ringand travelled with the engine oil to the scavenge side of the oil pump. Debris from the anti-rotation tab triggered the engine chip detector light. Parts of the anti-rotation tab got trapped between a scavenge pump gear and the wall of the scavenge pump housing. The oil pressure pump and scavenge pump stopped. The drive shaft coupling from the fuel control gearshaft to the oil pump gearshaft fractured. There was no oil pressure and no N1 indication. The gas producer turbine and power turbine were still running. A stopped scavenge pump resulted in no warm engine oil flowing from the engine to the airframe oil tank, where the engine oil...
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