Fatal GOM B407 Offshore Take Off Accident: Safety, Helideck & SAR / Emergency Response Questions
Fatal Gulf of Mexico Bell 407 Offshore Take Off Accident: Safety, Helideck & SAR / Emergency Response Questions (RLC N595RL, Walters/IOC WD-106 Installation) – Updated After NTSB Final Report Issued 16 Jan 2025 In 29 December 2022 Bell 407 N595RL of Rotorcraft Leasing (RLC) crashed on take off from the West Delta 106 (WD106) offshore installation in the Gulf of Mexico (GOM). The pilot and 3 passengers died. On Friday 13 January 2023, the US National Transportation Safety Board (NTSB) issued their preliminary report into this offshore helicopter accident. UPDATE 22 January 2025: The NTSB issued their final report on 16 January 2025, prior to the renaming of the GOM, and we have updated this article. The Pilot The NTSB final report reveals the pilot was hired by RLC on 12 September 2022, just 3.5 months before the accident. His resume reported the following experience, including working for 5 onshore operators (the S-60 time should be S-70/H-60): On 28 September 2022, the pilot completed RLC’s initial ground and flight training (which included 16.8 flying hours, 7 offshore), and became a pilot-in-command (PIC) in the Bell 407 helicopter. RLC evaluated the pilot as satisfactory for the ‘Dynamic Rollover (Oral)’ and ‘Pinnacles or Platform’ requirements. The pilot’s total flight experience in helicopters, including the 155.8 flight hours flown with RLC, was 1,667.8 hours, of which 1,343.8 hours were flown as PIC at the time of the accident. The pilot had operated to and from WD106 a total of 23 times (GOM pilots are frequently assigned to contracts with specific customers serving a small number of installations). The pilot was on a 14 day on, 14 day off roster. He had been in Brazil during his most recent time off and travelled back on the day before the accident. That would involve a 9:20 hour international flight, a 1:50 hour domestic flight, plus a drive of c 2:40 hours. The NTSB did not determine their exact schedule. Based on current flight options this journey either involved leaving late on 27th with an overnight international flight and arriving early afternoon the day before the accident or worse, arriving after midnight on the day of the accident. The lead pilot stated that the pilot arrived for work at 05:30 on the day of the accident. The Accident Flight The helicopter departed South Lafourche Leonard Miller Jr. Airport (KGAO), Galliano, Louisiana with 4 passengers for WD106 on a VFR flight, 51.6 nm to the SE, at 07:48 Local Time. The outbound flight appears to have been uneventful. WD106 is owned by Houston based Walter Oil & Gas Corporation, and was constructed in 1994. On its SE corner WD106 has a 24×24 ft square helideck, which gives a 7.3 m D-value. The B407 has a 13 m D-value so this is a small, 0.56D, sub-D deck. The RLC Ops Manuals treats such decks as “a restricted category helideck” and states that “the pilot may have to reduce load to operate safely”. The WD106 Touch Down / Position Marker (TDPM aka Aiming Circle) is 10 ft diameter according to the NTSB, but as evident in images and deck drawings its actually 20 ft diameter. The NTSB report the deck, which was at an elevation of 100 ft, had recently been repainted and the stairwell painted red. It...
read moreBlinded by Light, Spanish Customs AS365 Crashed During Night-time Hot Pursuit
Blinded by Light, Spanish Customs AS365 Crashed During Night-time Hot Pursuit (Eliance/SVA Airbus AS365N3 EC-JDQ) On 11 July 2021 Airbus AS365N3 EC-JDQ, operated by Eliance for the Spanish Customs Surveillance Service (Servicio de Vigilancia Aduanera [SVA]) impacted the sea while manoeuvring in pursuit of a smuggler’s boat. The two Fight Crew survived but a Customs Agent was died, having been trapped in the capsized helicopter. The Accident In the safety investigation by the Spanish the Civil Aviation Accident and Incident Investigation Commission (CIAIAC), issued in Spanish in December 2022, the investigators explain that the helicopter left its base at Algeciras, Cadiz at 01:20 for a routine patrol. The Straits of Gibraltar are notorious route for drug smuggling from North Africa. The Aircraft Commander (9,347 hours experience, 4,005 on type and c7,000 hours flying customs flights) was the Pilot Flying (PF). The Co-Pilot (5,935 hours, though only 14.5 on type having joined the operator 2 months earlier with a SAR & HEMS background) was the Pilot Monitoring (PM). The Customs Agent was in the cabin, in the front left seat, at a FLIR equipped work station. The aircraft was operating Night VFR rules. The investigation report makes no mention of Night Vision Imaging Systems (NVIS) googles being used. When they took off, the pilot at the controls the PF set their radalt bug to 300 ft and the other PM had theirs set to 500 ft. When descending below 500 ft the PM would re-set theirs to 100 ft. When they had been flying for approximately five minutes, they heard on the radio that an SVA vessel (Patrol Boat Águila 4 [a 17 m, 50 knot, Rodman 55]), based in the Port of Algeciras, was pursuing a boat and the Customs Agent offered to support them from the air in the chase. The crew of the Patrol Boat answered in the affirmative and provided them with their coordinates. The helicopter crew verified that the Patrol Boat was at a distance of approximately 35 NM to the east and began to move towards the area where the pursuit was taking place. The smugglers were taking a longer route to Spain. Which also meant operating further from cultural (i.e. man-made) lighting ashore. When they were south of Europa Point [site of the Trinity House lighthouse at the southern tip of Gibraltar], heading towards the coordinate point they had been given, they gradually descended from an altitude of 3,500 ft, until they reached the vicinity of the vessels, flying with 70% torque and a speed of 130 kt… When in pursuit of a vessel, the flight crew would turn on the landing lights. These were deployed but not turned on at this point. When slowing below 80 knots the PM armed the emergency flotation system. Crucially: There was a lot of humidity and scattered banks of fog…according to a statement from the PF. When the Customs Agent located the two vessels, using the FLIR surveillance system, he guided the crew with more precision until they positioned themselves close to them. When positioned to the left of the SVA patrol boat they descended “very rapidly” from an altitude of 500 ft to below 100 ft. There is no discussion on the use of any automation, the implication being that the descent was conducted manually. It can be presumed...
read moreHESLO EC135 LOC-I & Water Impact: Hook Confusion after Personnel Change
HESLO EC135 LOC-I & Water Impact: Hook Confusion after Personnel Change (DAP Helicopteros Airbus EC135T1 CC-CCA) On 22 December 2018 Airbus EC135T1 CC-CCA of DAP Helicopteros impacted the water of the Beagle Channel off Chile’s Picton Island after a Loss of Control – Inflight (LOC-I) while conducting Helicopter External Sling Load Operations (HESLO) from a ship. The aircraft sank 165 m from shore. The pilot, the sole occupant, was seriously injured but successfully egressed, swam to the remains of a pier and was recovered by boat. The Accident The accident was investigated by the Dirección General de Aeronáutica Civil (DGAC) Accident Prevention Department. Their safety investigation report was issued in Spanish only. They explain that the pilot (5,215 flying hours of experience, 651 on type) had conducted a number of HESLO cycles to transport loads to the ship. A large extra 25 kg hook was fitted as a safety weight to keep the 6.1 m sling vertical below the helicopter. Briefings were conducted with the ground parties ashore and on the ship and the need for this extra hook was emphasised. A maintenance technician from the helicopter operator had been on board the ship until c17:15 when he travelled ashore to prepare for refuelling. the helicopter. At 18:04 Local Time, having deposited a further load he pilot commenced manoeuvring away. Upon reaching a speed of 30 knots he heard a noise from the rear of the helicopter. The pilot of CC-CCA identified he no longer had any yaw control through the pedals. He slowed the aircraft to c 30 knots, descended towards 50 ft and commenced a turn to the right. As the helicopter slowed and the aerodynamical side load on the vertical stabiliser reduced the loss of yaw control became aggravated. Ultimately the pilot completely lowered the collective and the aircraft impacted the water, inverted and sank. The DGAC Safety Investigation Divers identified that was damage to the right hand side of the fenestron fairing and blades. However the large extra hook was not found with the helicopter but attached to the last container positioned on the ship. The pilot stated that while the helicopter was equipped with mirrors he was not able to always readily observe the hook. Investigators confirmed that the smaller sling load hook could reach the area of damage. Examination of GPS data confirmed the aircraft stayed below 69 knots (80 knots is the limit for HESLO). The helicopter was equipped with an emergency flotation system. It did not deploy. The investigation report does not discuss whether its activation had been commanded by the pilot but had failed or whether the system was not activated. DGAC Conclusions Cause: Loss of directional control of the helicopter during the flight, due to the impact of the hook of the load line against the tail rotor. Contributory Factors: Ship’s personnel unhooked the container from the permanent cargo, leaving the load line without its safety weight [the extra hook] The person in charge of giving the signal of conformity to the pilot did not realize that the line was left without its safety weight. The pilot did not realize that the permanent charge was not installed in the sling, because the mirror allowed him to partially see the line. The speed reached by the helicopter would have contributed to...
read moreDornier 328-100 Crossed Apron During Runway Excursion
Dornier 328-100 Crossed Apron During Runway Excursion (DANA 5N-DOX at Port Harcourt NAF Base) On 23 January 2019 Dornier 328-100 turboprop 5N-DOX of DANA (Dornier Aviation Nigeria AIEP Limited) suffered a significant runway excursion at the Port Harcourt NAF Base, crossing the airport apron and stopping just 3 m from the boundary fence. Nigeria’s Accident Investigation Bureau (AIB) released their safety investigation report on 30 December 2022. The aircraft was operating an oil and gas industry chartered flight from Bonny with 16 persons on board (2 Flight Crew, 1 Cabin Crew, 12 passengers, and 1 Aircraft Maintenance Engineer). The Co-Pilot (3,900 hours experience, 3,650 on type) was the Pilot Flying (PF) and the Aircraft Commander (18,400 hours, 6,500 on type) was the Pilot Monitoring (PM). On approach to PH NAF Base: According to the crew at 6.2 NM they noticed that number 1 engine was producing torque higher than the recommended 20% for final approach and landing. At flight idle, it was indicating 24%, whereas the number 2 engine was indicating the normal 20% torque at flight idle. At 10:00 h, [flight nember] DAV462 landed right of centreline runway 22. The crew also stated that, on idling the power lever during the landing roll, torque from number 1 engine increased to 27% instead of decrease below 10% causing a differential torque between the engines. It showed a maximum value of 34%. The torque from number 2 engine decreased below 10% (normal indication). The aircraft veered off the runway to the right…and was uncontrollable despite rudder application. BETA light were sighted and speed was higher than normal taxi speed. Emergency park brake was engaged. Specifically: [T]he aircraft exited the runway at a distance of 1,190 m from the threshold of runway 22. It further travelled on the runway shoulder for a distance of about 105 m. At a distance of approximately 98 m of its movement on the runway shoulder, the No. 4 right main tyre broke a runway edge light. The aircraft further veered off the runway shoulder and continued on the grass verge. It covered a distance of about 262 m on the grass verge. The aircraft travelled an additional distance of 259 m on the apron and came to a complete stop at about 3 m to the perimeter fence by the Aero Contractors ramp. The aircraft was slightly damaged. The occupants were all uninjured. Luckily there were no aircraft or vehicles on the apron in the path of the Dornier. The AIB Safety Investigation The AIB found the CVR data had been overwritten. The FDR showed a torque disparity of 20% (78/58) when at 6,000 ft 23 minutes prior to landing. There was an initial rudder displacement of 26° immediately after touchdown. The disparity in the left and right propeller torque values is an indication of failure of the propeller control unit (PCU) of the number 1 engine. Maintenance was conducted before investigators arrive: The aircraft technical logbook entry of 23rd January 2019 (post-occurrence) indicated: “L/H engine propeller will not come out of feather. L/H PCU [model D-1192-2] replaced IAW DO328 MM 61-21-04. OPS, Rig Check, Leak Check, OK”. Tyres were also replaced. The PCU responds to commands from the pilot’s “power and condition levers and controls and actuates the propeller hydraulically using oil from the...
read moreNight Mountain Rescue Hoist Training Fatal CFIT
Night Mountain Rescue Hoist Training Fatal CFIT (SAF Hélicoptères Airbus EC135T1 F-HJAF) On 8 December 2020 Airbus EC135T1 F-HJAF of SAF Hélicoptères suffered a Controlled Flight into Terrain (CFIT) at c 5,900 ft altitude in mountainous terrain in the French Alps during mountain rescue training. The helicopter was destroyed, 5 occupants died and the pilot was rescued with serious injuries. The Accident Flight The Bureau d’Enquêtes et d’Analyses pour la Sécurité de l’Aviation Civile (BEA) explain in their 109-page safety investigation report, issued 14 December 2022, that six training flights were planned, namely two morning, two afternoon and two night flights. These were conducted under an EASA Part-SPA.HHO specific approval for hoist operations. The operator’s SPA.HHO training approval had been issued by regulator the previous Friday, 4 December 2020. The operator had however previously been conducting rescue hoisting under a national approval and the trainees therefore had prior mountain hoisting experience. The exercises followed a day of classroom training on Monday 7 December 2020 and were… …designed for the trainees to obtain the SPA.HHO “Initial” and “Advanced Mountain” approvals taking into account their [prior] experience. The instructor pilot (who was also the NPCT [Nominated Person for Crew Training, appointed just 4 months earlier]) and the instructor hoist operator (who was also the NPFO [Nominated Person for Flight Ops]) were the only two people trained to deliver the training they had set up. There was a potential time pressure as the mountain rescue season was set to start on 12 December 2020 and two trained crews were contractually required. At the end of the afternoon, the two crews held a briefing before the two night flights. The review of the weather forecast had revealed that there would be a disturbance bringing snow in the evening. For the night flights, the crew was to consist an instructor pilot [the NPCT], a pilot under instruction, an instructor hoist operator [the NPFO), a hoist operator under instruction and two rescuers who were to be hoisted. After the first night flight a second pair of trainees were to replace the first. Given the arrival of this [weather] disturbance, the very short exercise programme (three hoist operations) and the proximity of the exercise site (situated 3.2 NM SE [of Albertville aerodrome] at an altitude of 6,000 ft), all the persons concerned took the decision to carry out the two flights one after the other and to switch crews with the rotor turning at the end of the first night flight.’ It was a moonless night. The aeronautical night (30 min after sunset) started at 16:22 at [near-by] Chambéry. The second night flight commenced at 17:00. The instructor pilot had 6,200 hours experience, 1,513 on type. The pilot under instruction had 5,493 hours experience, 663 on type. EC135T1 F-HJAF, manufactured in 1998, was equipped with traditional analogue avionics and didn’t have an autopilot. It did have a HELIMAP moving map display connected to a Trimble GNSS. On the way to the site, the instructor [pilot] identified fog banks on the northern slope of the mountain located to the north-east of the exercise site. On arrival the same three approaches and hoist exercises as conducted during the first night flight were repeated. Although the town lights in the distance were visible, they were only sufficient for choosing...
read moreS-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. ...
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