S-61N Accident in Afghanistan: Investigators Focus on Auxiliary Servocylinder
S-61N Accident in Afghanistan: Investigators Focus on Auxiliary Servocylinder (CHI Aviation Sikorsky S-61N N908CH) On 20 April 2020 Sikorsky S-61N N908CH of Construction Helicopters Inc (CHI Aviation), experienced a loss of control in flight and rolled on its side during an emergency landing at Camp Dwyer, Helmand Province, Afghanistan. The two pilots and crew chief onboard were all seriously injured. The helicopter was built in 1977 and its Aircraft Total Time (ATT) was 38,496 hours. It was conducting a Part 135 cargo flight under contract to the US Department of Defence (DoD). The Afghanistan Civil Aviation Authority delegated the investigation to the US National Transportation Safety Board (NTSB). The NTSB has so far only published an insubstantial preliminary report but did release the far more extensive Public Docket on 22 December 2022. There the NTSB explain that: The accident helicopter had an Appareo Vision 1000 image recorder installed n the ceiling of the cockpit. The image recorder was forward-looking, with a view of the instrument panel, a portion of the left and right seat cockpit controls, and a partial view of the outside via the lower portion of the windscreen. The Vision 1000 recording showed that c 8.75 seconds prior to the end of the recorded data from the accident flight, the left-hand pilot’s left pedal moved fully forward without pilot input. Consequently the helicopter yawed to the left for the rest of the recording. The cockpit auxiliary hydraulic pressure gauge indicator was within the green arc during this time, and indicated about 1,500 psi about 1 second prior to the left pedal movement, after which it dipped to 1,300 psi (near the bottom of the green arc). The NTSB did not visit the accident site but did direct on-scene evidence gathering and requested certain components be returned to the US for examination Examination of the auxiliary servocylinder assembly found a fatigue crack on the housing of the yaw channel pedal damper check valve as well as cracks and fractures on its bolts. The auxiliary servocylinder assembly has a 2,500 hour Time between Overhaul (TBO). The unit fitted to N908CH was released after its last overhaul on 1 September 2017 by JB Helicopter Accessory Service, a Canadian maintenance organisation at a Component Time Since New (CTSN) of 34,184 hours. It was fitted to N908CH in Afghanistan at ATT 37,102 Hours. However: On July 9, 2019, at an ATT of 37,611.5 hours, there was an entry in the discrepancy section of the daily flight log that stated “aux hydraulics leaking” and “aux servo yaw channel leaking.” The auxiliary servocylinder assembly was removed and had a CTSN of 34,694.0 hours and a CTSO of 509.6 hours. The auxiliary servocylinder was repaired from July-August 2019 at JB Helicopter Accessory Service… According to the repair paperwork, the yaw piston seals were replaced and the unit was returned to CHI Aviation in Afghanistan. After it was refitted: On November 11, 2019, at an ATT of 38,021.0 hours, there was an entry in the discrepancy section of the daily flight log that stated “yaw pedals move L/H during normal operation.” The corrective action section of the flight log stated the yaw open loop spring was adjusted. The recent maintenance history is therefore: NTSB note that: Sikorsky Safety Advisory No. SSA-S61-08-001, dated February 28, 2008, discussed...
read moreAutomation Issues During Night SAR Training – Near CFIT
Automation Issues During Night SAR Training – Near CFIT (Babcock Galicia Coast Guard Sikorsky S-76C+) On 26 July 2019 Sikorsky S-76C+ Search and Rescue (SAR) helicopter EC-JES of Babcock España, an entity Babcock has since entered an agreement to sell, inadvertently descended to 22 ft above sea level during a night training exercise over the Vigo estuary in Galicia, Spain near Cabo Home. In the resulting safety investigation by the Spanish the Civil Aviation Accident and Incident Investigation Commission (CIAIAC) the investigators explain that the SAR crew had reported for duty at 22:00 Local Time. The helicopter took off from Vigo Airport [at 23:10], with a pilot, co-pilot, rescue swimmer, winch operator and instructor on board. In addition to being a training exercise, the winch operator was to undergo a SAR verification during the flight. This would involve a simulated rescue in the vicinity of a cliff. Cabo Home was a common location for training exercises. This training task had been attempted the day before but been called off due to fog. The helicopter was contracted to Galician Regional Government’s regional Coast Guard Service, which has helicopters at Vigo and Celeiro. It was being operated under a Certificado de Operador Aéreo Especial (COE), a Special Air Operator Certificate. The Spanish regulator AESA, has issued around 20 COEs to operators performing tasks outside the EASA Basic Regulation, such as SAR, aerial firefighting etc. At take off the Aircraft Commander or ‘PIC’ (5,170 hours total experience, 1,583 on type) was Pilot Monitoring but took over as Pilot Flying prior to reaching waypoint W (see below). Winds were light and wave height <2 m. There was little moonlight as: The moon was in an advanced last quarter phase, four nights before the new moon. This S-76C+ was equipped with a Honeywell SPZ-7600 Digital Automatic Flight Control System (DAFCS). The system is coupled to the three axes (pitch, roll and yaw, as well as the collective), and performs the functions of autopilot and flight director. It also incorporates additional functions that reduce the pilot’s workload: automatic trim, heading hold, coordinated turns and automatic levelling. The Aircraft Commander… ….engaged the IAS, NAV (navigation towards the mouth of the estuary) and ALT (over 1900 ft) modes. Meanwhile the Co-Pilot (4,806 hours total experience, but only 76 hours on type) was in radio contact with the Maritime Rescue Coordination Centre (MRCC) and ATC. Analysis of the Cockpit Voice Recorder (CVR) confirmed that: As the crew entered data into the FMS (Flight Management System), the commander explained the process to the co-pilot. The commander can be heard telling the co-pilot that he is activating ALT PRE and VS to descend to 500 ft. The information is copied by the co-pilot. The commander also indicates that he is reducing speed to 80 knots. CIAIAC explain further that: With regard to the use of the SPZ-7600 system controls, pilots initially select the ATT and FD1/2 modes on the PC-700 (1), then select several FD modes on the MS-700 (2). Before the descent, they select 500 ft of altitude on the AL-300 (3) to descend and maintain that height over the estuary, followed by the ALT PRE Mode on the MS-700 (2) and the desired descent rate of 800 ft followed by V/ S mode on the MS-700 (2). The...
read moreMain Rotor Blade Certification Anomaly in Fatal Canadian Accident
Main Rotor Blade Certification Anomaly in Fatal Canadian Accident (B206B C-GEBY with Van Horn Composite MRBs) On 24 September 2019 Bell 206B C-GEBY of E & B Helicopters crashed shortly after take off from Campbell River, British Columbia, striking a building and two vehicles. The pilot (16,122 hours total time, 5,642 on type), the sole occupant, died and the helicopter was destroyed by the impact and a post-crash fire. The Accident Flight The flight was intended to deliver supplies to a remote cabin at Moat Lake. The cargo (beer, groceries and firewood) was unsecured in the cabin (contrary to the requirements of the E & B’s Operations Manual). Two 20 lb cylinders of propane were also loaded in the baggage bay. The Transportation Board of Canada (TSB) explain in their safety investigation report, published 8 December 2022, that: Shortly after departure…the helicopter briefly levelled off at 615 feet above sea level, then began a descent. The investigation found that an engine power anomaly likely occurred while the helicopter was in cruise flight and, as a result, the pilot reversed course and entered a descent consistent with an autorotation. [A]t the accident site that the most aft section of the tail rotor drive shaft cover was found 25 m before the impact location, along the flight path. Impact marks on the drive shaft cover were consistent with it being struck by a main rotor blade; however, the underlying tail rotor drive shaft was not significantly damaged. Pieces of foam consistent with the material found in the core of the main rotor blades were located several metres from the accident site. There were 33 witnesses to the final 20 seconds of flight: 7 described a “whop whop” sound while the helicopter turned from south to north; 15 described either no engine sound or sounds associated with an engine not developing normal power; 15 described wobbly or erratic movement of the helicopter in the moments leading up to the accident; 6 described a rotor blade detachment, or something coming off the helicopter during the final moments of flight; 10 described a very slow or near-stopped main rotor rotation just before the departure from controlled flight; and 19 described a straight-in or vertical drop to the ground. CCTV footage of the impact indicated damage to the main rotor blades prior to the ground impact. The Safety Investigation Examination of the engine revealed: Aluminium shavings from crushing rotational contact between the compressor impeller and diffuser scroll had been blown back to the turbine section, but were not melted as they normally would be by the high operating temperatures found in the combustor section. This is consistent with an engine that has flamed out. TSB conclude that: An engine power anomaly likely occurred while the helicopter was in cruise flight and, as a result, the pilot reversed course and entered a descent consistent with an autorotation. Examination of the main rotor blades revealed… …several indications of structural failure in flight. At some point during the flight, both main rotor blades became deformed. Although indications of fatigue were present post-occurrence on a small portion of the trailing edge of one of the main rotor blades, the extent to which this fatigue contributed to the deformation could not be determined. The TSB go on to state that… …in...
read moreGuarding Against a Hoist Cable Cut
Guarding Against a Hoist Cable Cut (Leonardo AW139, New South Wales, Australia) At night on 22 April 2020 a Leonardo AW139 air ambulance helicopter hoisted paramedics into a remote area near Tumut. New South Wales to attend to bushwalkers who had requested assistance. The Australian Transport Safety Bureau (ATSB) report that shortly after this the paramedics requested that the helicopter assist by illuminating the area. ATSB do not identify the aircraft registration or the operator. As the helicopter moved into position, the hoist operator positioned himself to use the hoist downlight for the illumination task. This involved him holding the hoist control pendant in his left hand and reaching for the search light directional control switch on the hoist panel with his right hand. At this moment, the helicopter experienced a gust of wind that disturbed the steady hover and caused the hoist operator to partially lose his balance. In an attempt to stabilise himself, he held the door with his left hand and his right hand remained on or near the hoist control panel. As he was looking outside, the hoist operator’s gloved hand or wrist inadvertently flicked up the cable cutter guard and depressed the cable cutter switch in one movement, severing the hoist wire and resulting in the hook assembly falling to the ground. In fact, four years earlier the proximity of the cable cutter guard to the searchlight directional control had has been noted by the operator. Various procedural controls had been “enacted and/or refreshed at various times” and recorded in the operator’s Safety Management System (SMS). A Civil Aviation Safety Authority (CASA) approved third party modification introduced with the intent of reducing risk of inadvertent cable cut activation. This included both a cable cut shroud and restraint of the intercom lead (the latter aspect suggesting an intercom lead snag was an activation method under consideration). ATSB note that: This did not completely eliminate the risk, but did provide a measure of design protection. No detail is given on the design and assessment of this ineffective modification. Safety Action The locally modified shroud around the cable cut switch fitted at the time of the incident is illustrated below left. Leonardo released an optional Service Bulletin 139-557 in September 2019 for a hoist cable cutter frame “to prevent inadvertent cable cut lifting actions on the hoist control panel” (above right). After the 22 April 2020 NSW incident they issued revised Alert Service Bulletin 139-637 in June 2020 and the European Union Aviation Safety Agency (EASA) made this mandatory through Airworthiness Directive 2020-0131 (promptly effective on 12 June 2020). It stated: This condition, if not corrected, could lead to further unintended activation of the hoist cable cutter, possibly resulting in injury to a human load or to persons on the ground. ATSB note that… …the operator considers that a design relocation of the searchlight control switch would reduce the risk of inadvertent activation to as low as reasonably practicable. The aircraft operator…[has] undertaken a preliminary assessment to have the searchlight control switch moved from the hoist control panel and have it incorporated into the hoist operator’s pendant control. This will remove the need for the hoist operator to have their hand in close proximity to the cable cut switch on the hoist control panel while operating the searchlight directional switch....
read moreWhiteout During Avalanche Explosive Placement
Whiteout During Avalanche Explosive Placement (Kootenay Valley AS350B3 C-GWTQ) On 16 March 2022, Kootenay Valley Helicopters‘ Airbus AS350B3 C-GWTQ crashed while conducting avalanche control operations north of Nelson Aerodrome (CZNL), British Columbia (BC). The Accident The Transportation Safety Board of Canada (TSB) explain in their safety investigation report, issued on 2 November 2022, that the helicopter was contracted by the British Columbia Ministry of Transportation and Infrastructure (MOTI), and onboard was the pilot (c11,000 flight hours, “mostly” on the AS350) and two ‘avalanche technicians’ (who both had c20 years experience in the role). The BC MOTI’s Avalanche and Weather Programs unit has a published manual, Explosive Use Operational Plan, that specifies that the Ministry artificially triggers avalanches to reduce the threat of naturally triggered avalanches along provincial highways. The team were making their second flight of the day to drop “strategically placed explosive charges (12.5 kg bags of ammonium nitrate and fuel oil [ANFO] compound) and igniters onto the slope from a height of approximately 20 feet”. The crew were the same as on the first flight, but the avalanche technicians exchanged roles and positions. The bombardier was seated on the right side of the rear bench… His role was to deploy charges out of the right-side pocket door. He coordinated the placement of the helicopter with the pilot to achieve the best effect from the explosive charge. The role of the blasting assistant, who occupied the left front seat, was to document the operation. The helicopter operated approximately 100 feet below the London Ridge ridgeline, about 7000 feet above sea level (ASL). The plan was to deploy 15 explosive charges. The bombardier requested an adjustment to the initial target for the second explosive charge to be deployed, and the pilot climbed the helicopter up the slope, nearer to the ridge and close to the base of the clouds. The pilot’s exit strategy would be to turn left and then fly downhill if necessary. As the helicopter progressed along the mountainside near the upper treeline, the pilot positioned and stabilized it in a hover to allow the explosive charge to be deployed. Just as the pilot lost reference with the ground and flight visibility was reduced, the bombardier deployed the second explosive charge. At this time, the main rotor downwash and prolonged hover over a layer of loose snow created whiteout conditions. As anticipated the pilot turned the helicopter to the left. During this manoeuvre the tail rotor contacted either a tree or the surface of the slope; this caused the helicopter to shudder. The high-frequency vibration rapidly worsened and the pilot performed a forced landing. [T]he helicopter landed hard on its skids and tipped onto its right (the pilot’s) side [and] came to rest about 3 to 5 m downslope of the second explosive charge deployed. The charge detonated approximately 2.5 minutes later, but did not trigger a release of the snowpack. The occupants were disoriented and shaken, but uninjured. The pilot and blasting assistant were able to extricate themselves from the wreckage. The bombardier required some assistance to release his harness because his own knife was not easily accessible. He also experienced difficulty releasing his lap belt because the latch mechanism had been taped over. This was a working practice to prevent a snag hazard opening the latch. ...
read moreImpatience Comes Before a Fatal Fall During HESLO
Impatience Comes Before a Fatal Fall During HESLO (Heliscan Airbus AS350B3 LN-OYH) On 16 November 2021 Airbus AS350B3 LN-OYH, operated by Heliscan, was involved in a fatal Helicopter External Sling Load (HESLO) accident at Åsäng, in Västernorrland County, Sweden. A member of the ground part got caught by the cargo sling, was lifted into the air and fell. The Accident The Swedish Accident Investigation Authority (Statens haverikommission – SHK) explain in their safety investigation report, issued on 7 November 2022, that… …Heliscan was transporting timber…on behalf of the Västernorrland County Administrative Board. Heliscan had three people assigned to this job: a pilot, a loadmaster and a refueller. On the day before the occurrence, final preparations were made at Heliscan in Östersund. At this time, the staff involved went through the job and prepared the equipment. The refueller (59) was not present at that briefing but was briefed that evening by the pilot (33, with 984 hours of flying experience, 804 on type). The company’s Ops Manual states that the pilot is ultimately responsible on site for implementation of the task. Ahead of the job, the [pilot] conducted a final risk assessment on site in accordance with the company’s document Safe Job Analysis. On the day of the accident: As a result of high surrounding terrain and tall trees, the pilot made the decision to use a 10 m long extension to the sling, which meant that the total length was 25 m. In addition, some loads that had to be transported to places that were difficult to access were extended with an extra cargo strap that was 6 m long. These extra straps were attached to the prepared loads of timber using a shackle. Using…an extension [strap] on certain loads meant that the safe distance to obstructions in certain places was improved. However, the fact that the extension was attached to the load that was on the ground entailed an increased risk of these straps lying free on the ground, which thus increased the risk of becoming caught in them. …no specific risk analysis was conducted in respect of attaching an extra strap to the loads. We discussed a similar hazard back in 2014: Keep Your Eyes on the Hook! Underslung External Load Safety The loadmaster was responsible for preparing then loads and had an assistant from Länsstyrelsen. They both had radio contact with the pilot and were meant to be the only people near the load when the helicopter approached. The refueller did not have a radio. This was a conscious decision to minimise distraction radio transmissions. However, earlier in the day of the accident the refueller had attached loads, despite this not being part of his duties, though he had worked as a loadmaster for another helicopter operator for 30 years. He was not a pilot and Heliscan’s philosophy is that all their loadmasters should be pilots. The loadmaster and the refueller knew each other well and, prior to the day in question, had spoken several times about how the work would be conducted on site. The loadmaster was concerned that the refueller would not stick to his specific task and would instead step in and work in the high-risk area as well. The loadmaster had repeatedly asked the refueller to simply stick to the refuelling, most...
read moreMind the Gap: Hover Taxi Collision
Mind the Gap: Hover Taxi Collision (Bell 206L) On 30 July 2022 a Bell 206L was hover taxiing from the fuel bowser to park at Newman Airport, Western Australia when the main rotor stuck a hangar. The Australian Transport Safety Bureau (ATSB) occurrence brief identifies neither aircraft or operator. They explain that: While lining up with marking aids on the taxiway, the pilot directed their attention towards a nearby parked helicopter to the right to ensure adequate clearance from the Bell 206L’s main rotor blade. As the pilot moved the 206L forward into the parking bay, there was a loud bang. The pilot reported there was no loss of control or abnormal movement after the sound and continued to land and shut down the helicopter without further incident. During the post-flight inspection, it was identified that one main rotor blade had contacted the end of the gantry which supports the sliding doors of the hangar. The helicopter sustained damage to the main rotor blade tip cap over about 10 cm. Safety Actions According to ATSB: The operator suspended helicopter operations around the apron area where the incident occurred, pending the outcomes of an internal investigation into the incident. The operator will also review the risk analysis of the apron parking in the vicinity of the hangar and assess the current helicopter parking configuration. ATSB Safety Message The FAA helicopter flying handbook advises that when taxiing near hangars or obstructions, the distance between the rotor blade tips and obstructions is difficult to judge. To reduce collision risk, operators should consider human limitations in assessing the hazards and ensure crews maintain situational awareness of the aircraft’s established safe distance for separation from all objects during taxi. Risk assessments on apron parking areas should be reviewed periodically to re-evaluate risks and mitigations. 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: Taxiing AW139 Blade Strike on Maintenance Stand S-92A Collision with Obstacle while Taxying Pedestrian Seriously Injured by Air Ambulance Landing at Melbourne Hospital RLC B407 Reverses into Sister Ship at GOM Heliport Pilatus PC-12 Collided with Pick-Up Truck During Dusk Take Off Investigation into Collision of Truck with Police Helicopter SAR Hoist Cable Snag and Facture, Followed By Release of an Unserviceable Aircraft South Korean Fire-Fighting Helicopter Tail Rotor Strike on Fuel Bowser Ditching after Blade Strike During HESLO from a Ship US BSEE Helideck A-NPR / Bell 430 Tail Strike UK AAIB Report on Two Ground Collisions Ground Collision Under Pressure: Challenger vs ATV: 1-0 Fatal ATC Handover: A Business Jet Collides with an Airport Vehicle on Landing SAR AW101 Roll-Over: Entry Into Service Involved “Persistently Elevated and Confusing Operational Risk” Second Time Unlucky: Fatal Greek Wirestrike High-Wire Illusion Runaway Dash 8 Q400 at Aberdeen after Miscommunication Over Chocks Gazelle Caught Out Jumping a Fence Helideck Safety Alerts: Refuelling Hoses and Obstructions Air Ambulance Helicopter Downed by Fencing FOD Snagged Sling Line Pulled into Main Rotor During HESLO Shutdown Ambulance / Air Ambulance Collision Hazardous Hangar Hovertaxy The UK CAA has issued this infographic on distraction: 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 moreSuspected Drone Strike on Helicopter
Suspected Drone Strike on S300C Helicopter N2158T On 23 June 2022 Schweizer 300C N2158T struck an object when 500 ft AGL over Boonville, North Carolina. The US National Transportation Safety Board (NTSB) explain in their safety investigation report, issued 1 November 2022, that the pilot, who had 14,000 hours of flying experience, had looked up after radio frequency change to see… …a “drone hovering” in the path of the helicopter. He reported that it struck the main rotor disk at the 2 o’clock position and it “disintegrated.” The pilot evaluated the helicopter for vibrations or damage and elected to return to the departure airport, which was 3.5 miles away. Substantial damage was found on one main rotor blade. Main Rotor Blade (MRB) Damage to Schweizer 300C N2158T (Credit: NTSB) A sample was taken at the site of the main rotor blade damage and tested negative for bird DNA. However: A search for the unmanned aerial system was performed, however, no device was located. No Low Altitude Authorization and Notification Capability (LAANC) authorizations were requested for the area at the time of the accident. Additionally, no operational waivers had been filed with the Federal Aviation Administration for unmanned aerial system operations in the area at the time of the accident. The NTSB Probable Cause was an inconclusive: The helicopter’s impact with a non-biological object, which resulted in substantial damage to a main rotor blade. 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: Drone / Helicopter Mid Air Collision over LA City Hall ‘Probable’ Say NTSB Helicopter / Drone Mid Air Collision Filming Off-Road Race 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, Blue Sky @aerossurance.bsky.social and Twitter @Aerossurance for our latest...
read moreDouble Trouble: An Operator Lost Two Helicopters in the Same Lake in 12 Hours
Double Trouble: An Operator Lost Two Helicopters in the Same Lake in 12 Hours On 26 April 2022 two helicopters of Coastal Air Services, both performing Part-137 aerial application operations, crashed into Lake Apopka, near Oakland, Florida, just 12 hours apart. Accident 1: B206B N206BX At 07:16 Bell 206B N206BX, was being flown by a 55 year old pilot with 10,725 hours of experience, 3,087 on type. It was one of three helicopters conducting spraying (most likely for mosquito control). Spraying is typically done at 7-15 ft. The US National Transportation Safety Board (NTSB) safety investigation report, issued 13 October 2022, explains: He stated that he established course on his spray line but “lost sight of everything looking forward due to the glare off the water and the sun position.” He recalled having no depth perception when he looked down at the water and could not recall the helicopter impacting the water but recalled a momentary shudder followed by the helicopter coming to rest inverted. The pilot egressed via the right hand front door and received minor injuries. In the accident report form the pilot recommended spraying with the sun behind the aircraft to reduce glare, commence operation later (i.e. when the sun is higher) and that boats on the water add peripheral cues. The NTSB Probable Cause was: A collision with water following a loss of visual reference to the water surface due to sun glare. The Transportation Safety Board of Canada (TSB) recently reported glare as a factor in a wire strike to a Robinson R44 C-FVPA. According to the NTSB after the accident to N206BX… …a safety briefing was held with the pilots, and they were instructed to maintain constant communications with the loader truck. During the safety briefing there was no insight available into the first accident. Flying resumed at 12:15. Accident 2: OH-58A+ N281SP At 19:00 ex-military Garlick Bell OH-58A+ N281SP was being flown by a 54 year old pilot with 16,835 hours of experience. This was only his second day flying for the company. He had woken at 04:00 and had started flying at c07:00. The NTSB explain in their safety investigation report that earlier… …that afternoon the pilot noted that it was difficult to judge his height above the water and advised another company pilot via radio of that fact. …the water was “like a mirror,” which hampered his depth perception. By 18:30 the pilot noticed there were no longer any Florida Fish and Wildlife Conservation Commission (FWC) air boats on the lake. He was operating slightly higher than normal at 15-20 ft and at c 55 knots. Later that evening, during a final application pass while he was looking down at the GPS, the helicopterimpacted the water. In this type of operation pilots use their AG-NAV GPS display to help fly the right spray line. The pilot received minor injuries (scraped shins). He was rescued by climbing on to the skids of the remaining helicopter. This was because the pilot had briefed his colleagues …that because of the alligators he had seen in the lake, if his helicopter went down…he would not be swimming out. The pilot explained during an NTSB phone interview that he had had a near miss during his first day of flying (15 April 2022) with the company...
read moreFire Extinguisher Cover Fenestron FOD
Fire Extinguisher Cover Fenestron FOD (Air Evac Lifeteam Airbus EC135P2+ N228MT) On 19 July 2022 air ambulance Airbus EC135P2+ N228MT of Air Evac Lifeteam was damaged by FOD when landing at Mount Vernon Airport, Illinois (caught on VIDEO, along with some bizarre groundcrew dance moves). According to the US National Transportation Safety Board (NTSB) safety investigation report (issued 22 September 2022): Shortly before touchdown, a cloth fire extinguisher cover from a nearby mobile fuelling unit was blown airborne from the main rotor system wash. The cloth fire extinguisher cover was ingested into the tail rotor (the fenestron). During the cloth fire extinguisher cover ingestion sequence, the fenestron hub flexed, the metal fenestron hub cover detached, and it was also ingested. The hub cover is held in place by six retaining clips in a lip around the inner circumference of the Fenestron hub. The pilot was able to land the helicopter without further incident. The helicopter sustained substantial damage to the fenestron. The operator explained to the NTSB that this type of cover did not have any form of lanyard but it was common practice to secure the bag under the extinguisher’s metal retaining band. It is not clear how this particular extinguisher was secured on the day. NTSB say that… The operator additionally reported that foreign object debris checks are conducted by crew members anytime they are on the pad and that the mobile fuelling unit is inspected during the daily fuel quality check. The operator also didn’t volunteer the associated procedures or training for these FOD checks and fuel system inspection. One might suspect that relying on employees looking for FOD “anytime they are on the pad” would be a relatively ineffective measure in this case, where the ‘debris’ was intended to be where it was. NTSB Probable Cause NTSB state the self evident probable cause: The inadequate securement of the cloth fire extinguisher cover, which resulted in it being blown off the fire extinguisher and ingested into the helicopter’s fenestron during the landing. No safety recommendations were raised. Footnotes The NTSB do make an incidental comment in their report that the (then) Accident Investigation Board Norway (now NSIA) had previously issued a safety recommendation regarding the securement of the fenestron hub cover. This related to an incident on 13 April 2006 to HEMS EC135P2 LN-OOD. That occurred when “a considerable amount of snow passed through the lower part of the Fenestron” when the tail contacted a snow bank during landing at a remote site That resulted in “permanent deformation of all the rotor blades” and a pulsating load that caused the cover to detach. This was however assessed as legally not an ‘unsafe condition’ as a release only occurs after FOD impact. Another fenestron cover was lost when on 19 November 2015 when EC135P2+ N36RX when the fenestron of that air ambulance ingested a towel that, for reasons that are unclear, was in an unsecured container near the landing site. After the 2015 accident the NTSB issued a safety alert: Helicopter Landing Sites: Free from Debris (SA-57). The operator of N228MT circulated this 2 days after their accident at the request of the “FAA“ (actually the NTSB). Sharp eyed readers will have spotted in the video a plastic water bottle being left unsecured on the fuel bowser too. 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: FOD and an AS350B3 Accident...
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