Flybe Fume Event (Part 1): Compressor Wash Maintenance Human Factors Case Study
Flybe Fume Event (Part 1): Compressor Wash Maintenance Human Factors Case Study (ERJ195 G-FBEJ) On 28 February 2019 Flybe Embraer ERJ-195 (ERJ-190-200 LR / E195) G-FBEJ was commencing takeoff in Exeter, bound for Alicante, when the flight crew detected a sweet-smelling odour and observed smoke entering the cockpit. The takeoff was abandoned and after smoke and fumes were reported in the cabin an evacuation commenced. This article, the first of two, will examine the cause of the fumes. The second will examine the evacuation. The Safety Investigation The UK Air Accidents Investigation Branch (AAIB) explain in their safety investigation report that: During overnight maintenance on the night before the accident, an engine compressor wash was carried out on G-FBEJ’s No 1 [GE CF34-10] engine. A high-power engine ground run was not performed following the compressor wash, resulting in residual cleaning solution remaining in the compressor bleed air ducts. This can lead to fumes or unusual odours entering the cockpit and cabin. There is sadly often over-enthusiasm for labelling occurrences as ‘Failure to Follow Procedures” (FFP) events and obsessing on classifying how and why personnel ‘violated’ procedures, applying crude culpability decision aids. This case study shows that approach is very misguided in limiting the potential for holistic systemic improvement. Fortunately, the “sole objective” of AAIB safety investigations “is the prevention of accidents and incidents, without the apportionment of blame or liability”. This investigation therefore did not fall for the biases that can occur in relation to procedures. The Safety Investigation: Compressor Wash Procedures General Electric recommends engine cleaning to reduce contaminant build-up and maintain engine performance. Compressor washes are performed by maintenance personnel, using a wash rig, which uses either water or a water and detergent mix. The engine wash rig used on G-FBEJ was fitted with two pressurised fluid tanks, one which contained water and the other a water/detergent mix. During operation, the fluid can be directed into a water-wash manifold installed on the engine, to dispense water/detergent into the compressor. The maintenance personnel used Engine Service Manual (ESM) task 72-00-00-100-801 ‘Engine performance recovery,’ revision date 31 March 2016. The task requires a minimum of two people, one to operate the engine and system controls in the cockpit and one to operate the compressor wash rig. The ESM advises that: For some environments, washing with a cleaning solution … may be more effective than washing with water only….If a cleaning solution is used, it is important to follow instructions for rinsing and drying-out the bleed systems. A caution states: FAILURE TO ADEQUATELY DRY THE INTERNAL ENGINE AIRFLOW COMPONENTS AFTER AN ENGINE WASH CAN RESULT IN ODOR-IN‑CABIN EVENTS WHICH HAVE CONTRIBUTED TO SITUATIONS SUCH AS AIR TURNBACKS AND ABORTED TAKEOFFS. PROPER ENGINE DRY-OUT IS IMPORTANT TO PREVENT THOSE SITUATIONS. The ESM lists several detergents, including Turco 5884 used by the operator, which the ESM states should be mixed one part detergent to four parts water (i.e. 20% detergent). Rinsing should be with water only. The AAIB go on (our emphasis added): One subtask describes the procedure to wash the internal engine airflow components with water only and an alternative subtask describes the procedure to do the wash with a cleaning solution. It recommends that to get the best cleaning results, two washes should be done as well as a soak period between application of the cleaner, followed by two rinses to make sure that the cleaning solution is removed. A further subtask...
read moreHuman Factors of a Mali Mid Air Collision
Human Factors of a Mali Mid-Air Collision (MAC): ALAT Tiger and Cougar, Operation Barkhane, near Ménaka On 25 November 2019 two French Army helicopters, Airbus EC665 Tiger (Tigre) HAD 6017/F-MBJQ and Airbus AS532UL Cougar 2272/F-MCGE, collided in mid-air during a combat operation as part of Operation Barkhane, near Ménaka in Mali. The two crew of the Tiger and the 11 occupants of the Cougar died in the accident. The Events Leading to the MAC Investigators of the BEA-Etat (BEA-E) explain in their safety investigation report (issued on 29 January 2021 in French only) that at around 17:00 Local Time helicopter crews at bases in Gao and Ménaka were put on alert after a ground unit had contact with the enemy. The intention was to launch two Gazelles from Ménaka and two Tigers from Gao. With four aircraft deployed it was decided to also deploy a Cougar from Ménaka with an Air Mission Commander (AMC). The Cougar also had six troops onboard to provide an IMEX, immediate extraction, capability. The Gazelles departed at 17:31 followed by the Cougar at 17:40. The Tiger’s departed at 17:37. This was to be a night operation, sunset was at 17:16, with the crews utilising Night Vision Googles (NVGs) and operating only with formation lights (visible from above and behind only). The Gazelles arrived on-scene at 17:50, followed by the Cougar 10 minutes later, with the Tigers expected at c 18:25. French troops were to the south side of a wadi (a small river valley). The engagement had had triggered a large ground fire to the north of the wadi and the helicopters from Ménaka initially search for enemy combatants fleeing behind the fire. The Gazelles identified a point of interest, called a zone of action (ZA), several miles north of the fire. At 18:19 the AMC… …asked the Tigers and Gazelles to stay north of the area, the Tigers to stay west of the wadi and the Gazelles to the east. All of the following AMC communications relate to mission management and rules of engagement, in relation to ground troops who insistently request fire, and the Ménaka command post. The Cougar then goes north then east to fly over the wadi east of the ZA. At 18:23 the leader of the Tiger flight announces that he will climb to a height of 2,000 ft (i.e. around 3,000 ft AMSL) and loiter 2 nm west of the area (by implication ZA). The Cougar and Tigers coordinate TACAN channels and a pressure setting of 1,013 hPa. At this point the Cougar is at 3,000 ft AMSL and the Tigers at 2,800 ft. The AMC then proposes a withdrawal of the Gazelle and the Cougar as no longer necessary. At 18:26 the Tigers and the Cougar had all climbed slightly, with the Tigers 2 nm west of ZA and the Cougar 8 nm to the north-east. Shortly after the Cougar crosses the wadi and heads south-west without announcing this movement. At 18:29 the Tigers split so that one aircraft can overfly French troops at their request. The AMC is however busy on another channel at this point. The lead Tiger goes into an orbit around ZA at 3,000 ft before climbing to 3,300 ft. The Cougar, still at 3,200 ft, now commenced its unannounced orbit of ZA. At 18:33 the Cougar and lead Tiger passed in opposite directions separated 300 m horizontally and 100 ft vertically at 66 and 100 knots respectively. Two minutes later, on...
read moreRCAF Investigate Defect on Newly Delivered CH-148 Cyclone (S-92)
RCAF Investigate Terminal Wire Lug Defect on Newly Delivered CH-148 Cyclone (S-92) The Royal Canadian Air Force (RCAF) is investigating a defect that was found on 148805, a newly delivered Sikorsky CH-148 Cyclone (an S-92 military derivative), on 30 November 2020. Investigators report: During the aircraft acceptance check for aircraft CH148805 [at 12 Wing, CFB Shearwater, Nova Scotia], avionics technicians inspected the #1 Power Distribution Unit as per the Fleet Work Instructions. Terminal wire lugs T1, T2 & T3 were found unsecured. T1 was missing its securing nut, washer and lockwasher but was still contacting its terminal stud. T2 & T3 were found hand tight. A Foreign Object Damage (FOD) check was carried out and all missing hardware for T1 lug was located just below in its cover panel. The investigators explain that: Traditionally, CH148 Cyclone aircraft delivery from the final assembly plant to 12 Wing Shearwater has been accomplished via contractor crewed ferry flights. Due to the COVID-19 environment, the ferry flight has been split between contractor and DND crews, changing crews at Bangor, Maine. Once the DND crew and aircraft arrives in Shearwater, an aircraft acceptance check is carried out. The investigation is working collaboratively of with the manufacturer to assess the root cause(s) of the occurrence. It is also reviewing the DND acceptance check for CH148 Cyclone aircraft. UPDATE 15 June 2021: The investigators reported that: The investigation found that poor visibility of, and difficult access to the connections, as a result of the two-tier system of the PDU, combined with improper terminal position and fitment of stiff wires likely led to false torque condition. The preventive measures recommend a publication amendment, and a design change to prevent the nuts at the terminal connections from backing off when subjected to vibrations. 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: S-92A Flying Control Restriction on Wiring Loom PA-34 Electrical Short Melted Rudder Cable Embraer ERJ-190 EWIS Production Quality a Factor in Fire Fire-Fighting AS350 Hydraulics Accident: Dormant Miswiring UPDATE 9 April 2022: SAR Seat Slip Smash (RCAF CH149 Leonardo Cormorant LOC-I) UPDATE 17 September 2022: Canadian B212 Crash: A Defective Production Process UPDATE 25 May 2025: CHC Sikorsky S-92A Seat Slide Surprise(s) 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 moreInexperienced IIMC over Chesapeake Bay: Reduced Visual References Require Vigilance
Inexperienced IIMC over Chesapeake Bay (Guimbal Cabri G2 N572MD): Reduced Visual References Require Vigilance Just after noon on 4 May 2019, the privately flown Guimbal Cabri G2 helicopter N572MD, was destroyed near Kent Island, Maryland, with the loss of both pilot and passenger, when it impacted the water. The Accident Flight The US National Transportation Safety Board (NTSB) explain in their safety investigation report that the flight was planned so the passenger could take photos of a family member’s fishing trip in Chesapeake Bay. The pilot was aged 38 and had just 103.5 hours flight time in total, all in the Cabri G2. He neither held an instrument rating nor undertaken any instrument training. The flight school‘s rental agreement for the aircraft limited flight when flying without a flight instructor to VFR operations with a 3,000-ft ceiling and 6 miles visibility. The Cabri G2 is also not cleared for IFR operations. The passenger texted the family member at…1036… “The closer you stayed at [sic] Poplar Island the better chance we might have [of] finding you with this low ceiling there’s flight restrictions.” The National Weather Service issued an update at 1045 for AIRMET Sierra, which indicated IFR conditions for the area surrounding the accident location and advised of ceilings below 1,000 ft, visibility below 3 statute miles, precipitation, mist, and fog. The pilot called flight services at 1102 to file a special flight rules area (SFRA) flight plan for a local flight originating from Tipton Airport (FME), Fort Meade, Maryland. During the phone call, the flight briefer noted that instrument meteorological conditions (IMC) prevailed…and that he could not recommend a visual flight rules flight. Furthermore, he stated that AIRMET Sierra was issued for instrument flight rule (IFR) conditions and was currently active and ending between 1700 and 2000. The briefer asked the pilot if he needed a standard weather briefing and the pilot responded that he did not need any other information. An IFR plan was filed. At 1145, the passenger texted…that the helicopter was en route. At 1151, the family member sent the passenger the GPS location and the passenger responded at 1202, “Rats. You guys are too far west… flight rules.” Images taken by the passenger as the helicopter headed east along the Chesapeake Bay Bridge to Kent Island were compared with geographic data and indicate low visibility early in the flight: The NTSB don’t comment, but the altitude appears to be around 200-250 ft and the lateral offset perhaps 300 ft. At 1203 the family member sent another GPS location to the passenger and the passenger responded at 1208, “Can you see us? We are hitting the wall that we can’t fly through.” The family member responded, “not really” and the passenger sent one last text message at 1208 stating, “Give me one more pin to try.” There were no further communications with the passenger. The helicopter impacted the Chesapeake Bay about 1.5 miles from the [southern] shoreline of Kent Island… The NTSB Safety Investigation The wreckage was recovered from a 63 ft depth. Examination revealed no evidence of any pre-impact anomalies. Federal Aviation Administration (FAA) radar data (marked with UTC time – Local +4) shows the helicopter… ….flew over Kent Island and made several left and right turns over the southern tip of the island then flew about 2 miles south of the island. The helicopter manoeuvred in that area beginning at 1200 until radar contact was lost at 1211. The radar shows the helicopter was flying about 175 ft AMSL for the final...
read moreEngine Shutdown Results in Revised SOV Rigging Instructions
Engine Shutdown Results in Revised SOV Rigging Instructions (Dassault Falcon 2000EX HB-IAU) On 4 October 2018 Dassault Falcon 2000EX HB-IAU suffered a rare Pratt & Whitney Canada (PWC) PW308C turbofan engine failure mode when an emergency fuel shut-off valve (SOV) “activated because of its incorrect rigging” say investigators. Rather than simply dismiss this as a “Failure to Follow Procedures” following the investigation the manufacturer is enhancing its maintenance instructions. The Incident Flight The business jet took off from Zurich for Paris at 06:43 UTC, with two flight crew, a cabin attendant and two passengers. The commander was the pilot flying (PF), the copilot the pilot monitoring (PM). The Swiss Safety Investigation Board (SUST) explain in their safety investigation report, issued on 19 January 2021, that: As the aircraft was climbing through Flight Level (FL) 70 about two minutes after take-off, the flight crew heard a dull bang and noticed the failure of the right [No. 2] engine. The copilot tried to inform the air traffic controller about the engine failure and realised that radio No. 2 was inoperative. Using radio No. 1, he repeated the transmission, this time successfully, and requested immediate radar guidance for a return to Zurich… The flight crew realised that the autopilot and the elevator trim had also failed. At the suggestion of the copilot, the right bus-tie (rotary switch) was closed and both systems worked again. In addition, because of the bang, the commander decided not to attempt an engine restart. The copilot repeatedly advised the commander to declare an emergency, which he did at 06:52 UTC… The aircraft made a safe landing at 06:59 UTC, however only after difficulties with interception of the localiser for runway 14. The SUST Safety Investigation and Conclusions The SUST say that the electronic engine control unit data “did not give any indication of a malfunction of the engine”. However, when the engine was examined the emergency fuel shut-off valve was found to be closed. This valve is only intended to stop fuel supply if the event of a low-pressure turbine shaft failure. It is permanently open and can be closed rapidly and irreversibly only once by moving its actuating lever beyond a trigger point. This happens automatically and cannot be influenced from the cockpit. The control lever has an adjustable connection to a Bowden cable. The No 2 engine had been installed on 2 October 2018 after repairs. The rigging of the emergency fuel shut-off valve was checked. The next day, training flights were carried out with the HB-IAU without complaint. [O]n 4 October 2018…it was determined that the rigging was outside the tolerance range. The valve was readjusted in accordance with the applicable maintenance data. A follow-up check carried out after four further flights on 16 October 2018 showed that the rigging had shifted again by 0.050 inches. The subsequent adjustment had to be repeated three times until a stable result was obtained. SUST comment that: The description of the adjustment procedure in the current documentation is very complicated. An in-depth investigation finally revealed, when pulled by hand, the Bowden cable leading to the valve was stiff, difficult to move and jerky, and that the restoring force of a spring installed inside the valve was reduced. [PWC] stated that the reason for the closure of the emergency fuel shut-off valve could not be determined with certainty and that the valve and the Bowden cable...
read moreFatal US Helicopter Air Ambulance Accident: One Engine was Failing but Serviceable Engine Shutdown
Fatal US HAA Accident: One Engine was Failing but Serviceable Engine Shutdown (Air Methods / Duke Life Flight, Airbus Helicopters BK117C2 / EC145 N146DU, North Carolina) On 8 September 2017 Air Methods Corp (AMC) helicopter air ambulance (HAA) Airbus Helicopters BK117C2 / EC145 N146DU, operated for Duke Life Flight (DLF), crashed in a field close to an Amazon wind farm at Belvidere near Hertford, North Carolina. The helicopter was making a daytime 130 nm inter-hospital transfer from Sentara Albemarle Medical Center, Elizabeth City, NC for the Duke University North Heliport in Durham, NC. The 4 occupants (pilot, two medical personnel and patient) were killed. The S National Transportation Safety Board (NTSB) concluded this was a type of human factors related accident that has been termed a Propulsion System Malfunction + Inappropriate Crew Response (PSM+ICR) accident. The Accident The NTSB explain in their safety investigation report (issued in late January 2021), that during the flight: …the No. 2 [Safran Helicopter Engines Arriel 1E2 turboshaft] engine experienced a bearing seizure; the engine continued to run. It is likely that the pilot then errantly shutdown the No. 1 engine and continued to fly for a brief period utilizing the No. 2 engine. Several witnesses reported smoke trailing behind the helicopter. It is likely that the No. 2 engine subsequently lost all power. The helicopter then impacted a shallow turf drainage pathway between fields of tall grass on a farm, and a postcrash fire ensued, which consumed most of the helicopter structure. The lack of any ground scars leading toward or away from the main wreckage indicated that the helicopter was in a near-vertical descent before impacting the ground. One rotor blade was found intact [and] consistent with little or no rotation of the main rotor system. The NTSB Safety Investigation The helicopter’s Vehicle and Engine Multifunction Display (VEMD) was found in the wreckage, but no usable data were recovered because of the thermal damage to the non-volatile memory chip. The Honeywell MK XXI Helicopter Terrain Awareness System (HTAWS) was also destroyed in the fire. The helicopter was equipped with a North Flight Data Systems OuterLink Voice and Video Recorder… The device’s memory card was not damaged, but no usable data could be retrieved, including recordings of the accident flight. The manufacturer of the device indicated that its internal replaceable battery might have expired, which would have prevented new data from being properly stored on the memory card. NTSB don’t examine the maintenance or ay flight data monitoring (FDM) conducted by AMC on the system. The aircraft was not fitted with nor required to carry a crashworthy recorder. NTSB note that: The helicopter was equipped with a Honeywell Sky Connect Tracker II system that transmitted data to the DLF communications center and the [AMC Operational Control Center] OCC [in Greenwood Village, Colorado]. At the time of the accident, AMC had the Sky Connect Tracker II system configured for data transmissions emitting from the helicopter every 120 seconds. [This was not] a sufficient frequency to determine the helicopter’s track, speed, and descent profile before impact. [I]t is possible that the pilot was attempting an emergency OEI landing when the loss of power in the No. 2 engine occurred. [T]he helicopter might have been at an altitude that was too low and/or an airspeed that was too slow to allow for a successful autorotative landing when the loss of power in the No. 2 engine occurred. A reconstruction of witness statements using the innovative Immersive Witness Interview application from IWI indicated that “that the forward speed almost completely consumed before the vertical descent started”...
read moreBK117 Impacts Sea, Scud Running off PNG
Airbus Helicopters BK117C1 Impacts Sea, Scud Running off PNG (Tribal Aurora Helicopters, P2-TAH) On 13 September 2019 Airbus Helicopters BK117C1 P2-TAH (formerly UK HEMS G-RESC), operated by Tribal Aurora Helicopters (TAH), was making an over sea VFR positioning flight from Buka to Tokua in Papua New Guinea (PNG), when it impacted the sea approximately 2.7 nm SE of Silur. The pilot was killed, but the passenger, a company engineer, was rescued. The Accident Flight The PNG Accident Investigation Commission (AIC) explain in their safety investigation report (issued on 31 December 2020) that the 49-year-old pilot had c11,500 hours of flying experience, 300 on type. The pilot did not have a current IFR rating. Early in the flight the helicopter deviated slightly from its intended track descended from 2,540 ft to 1,333 ft. to avoid entering adverse weather. The investigators determined that about 30 minutes later, at about 01:03 UTC (11:03 Local Time), the helicopter entered IMC. At that point the passenger recalled… …the pilot revising the destination on the GPS from Tokua to a position which he believed was the nearest land, around the South East coastal area of New Ireland. The helicopter subsequently entered an area of heavy rainfall with thunderstorms. The last recorded data point at 01:15 showed the helicopter at an altitude of 217 ft and groundspeed of 62 kt, less than a mile from the Southern coast of New Ireland. Based on the passenger statement, the AIC determined that after the last recorded data point and as the helicopter continued tracking towards the revised position, it descended and slowed down to less than 5 kt prior to impacting the water. Flight Following, Survival and Search and Rescue (SAR) According to the passenger, they had worn their life jackets before the flight commenced. He reported that when the aircraft impacted water, he got knocked unconscious. When he regained consciousness, he noticed that the helicopter was underwater and air bubbles were escaping through the forward windshield frame. He looked to the right and saw that the pilot was missing. The passenger reported that he removed his seatbelt and followed air bubbles through the forward windshield frame and swam to the surface and inflated his lifejacket. After surfacing, the passenger recalled sighting the pilot at a distance and tried calling out to him but because it was windy and the waves were almost 5 m high, he lost sight of the pilot again. That was the last time he saw the pilot There was no [Artex C406-2 HM] Emergency Locator Transmitter (ELT) signal transmitted after the impact. The SAR Uncertainty Phase was declared by Air Traffic Control 3 minutes after the ETA at 01:28 UTC, this was rapidly raised to the Alert Phase and then the Distress Phase at 01:55 UTC. The Operator stated that they had not been monitoring the helicopter on Spidertracks [sattelite tracking] during the accident flight, however they were alerted by the pilot of P2-MUM [a Bell 430 of Manolos Aviation] at 02:03 that ATC was trying to contact P2-TAH and there was no response. The Operator immediately commenced their Emergency Response Plan…by discussing what was showing on Spidertracks at that time. The last mark showed the aircraft just off the shore of New Ireland, less than 1 minute from the land. Therefore, the Operator assumed the aircraft had probably landed due to weather and with only 30 second shutdown on the engines, that...
read moreUS Air Ambulance Near Miss with Zip Wire and High ROD Impact at High Density Altitude
US Air Ambulance Near Miss with Zip Wire and High ROD Impact at High Density Altitude (Trans Aero MedEvac HEMS Airbus AS350B2 N894NA) On 29 September 2018 Airbus Helicopters AS350B2 air ambulance N894NA of Trans Aero (dba Trans Aero MedEvac) was damaged in a landing accident, caught spectacularly on video, at the Ski Apache ski resort in southern New Mexico, on the slopes of Sierra Blanca mountains. The pilot and two medical personnel on board were uninjured. The Accident Flight The US National Transportation Safety Board (NTSB) explain in their safety investigation report (issued in January 2021) that the aircraft was inbound to collect a patient at a landing site at 9,793 ft AMSL. NTSB statements from the pilot and medical personnel onboard indicate they originally anticipated collecting the patent from Sierra Blanca Regional Airport (SRR), Ruidoso, New Mexico (a lower but still significant 6,814 ft AMSL). One of the medical personnel on board recount that: Enroute, while going over the mountain, there was a quick discussion between the crew regarding the density altitude of the landing zone due to the high altitude. Also, the crew was trying to contact the Ski Apache ground personnel but they were not able to attain to reach them until there were in the area of the landing zone. The pilot (aged 53, with 16,818 flying hours experience, 3526 on type)… …decided to conduct an eastbound reconnaissance over the landing site to scan for obstacles. He saw two cables in front and below the helicopter ‘s flightpath and initiated a go-around. It was only during this reconnaissance that they had made radio contract with the ground. These cables were in fact the ‘Palmer‘ zip wires at the resort. The landing site appears to be less than 130 m from the cables. It is not clear if the zip wires were in use, although the resort’s procedures are to halt their use when a helicopter was called. A UAE SAR AW139 did crash on 29 Dec 2018 after a zip wire strike. Oddly, part of the drill for preparing the landing site was to place thin orange tape on the ground under the zip wires in the hope this would be seen by the inbound pilot. The NTSB don’t elaborate further on the near miss or the landing site but go on to say the pilot…. …added power to clear the cables, and once the tail cleared the cables, he lowered the collective due to a slight drop in the main rotor speed. As he continued the go-around, he initiated a 180º left turn to attempt an approach to the landing site. The pilot stated wind was “5 knots and variable inside the valley. My approach was now slightly faster than normal”. He was asked why he decided to turn the helicopter versus completing the go-around, he stated that he looked towards the east at their current heading and saw a trees that would not be ideal for an emergency landing site if they lost engine power. He could not further explain why he decided to turn the helicopter and in hind sight, he would have continued the go-around. During the westward approach and while the helicopter was about 20 ft above ground level, he raised the collective to reduce the descent rate, and the main rotor speed subsequently decayed. He felt that, due to the “faster than normal” descent rate, he would not be able to cushion the landing. Before touchdown, a medical crewmember spotted an elevated steel barrier cable...
read moreGrand Canyon Air Tour Tragic Tailwind Landing Accident
Grand Canyon Air Tour Tailwind Tragic Landing Accident (Papillon Airbus EC130B4 N155GC) On 10 February 2018 Papillon Airways Airbus Helicopters EC130B4 N155GC was destroyed in an accident within the Grand Canyon, near Peach Springs, Arizona during an air tour flight. Five of the occupants, British tourists, died. The pilot and one passenger sustained serious injuries. Although there was a loss of control, this accident has many potential systemic lessons. The Accident The US National Transportation Safety Board (NTSB) explain in their safety investigation report, released in January 2021, that this was the pilot’s third flight of the day from Boulder City Municipal Airport (BVU), Nevada. The last two were both to a site called Quartermaster, within the Grand Canyon‘s Quartermaster Canyon. The 600 x 150 ft landing area is on rough ground on a plateau at an elevation of 1,450 ft amsl, approximately 3,300 ft below the rim of the Grand Canyon. It provided limited approach options due to its topography. The area had no designated pads or marked touchdown and lift off (TLOF) zones, or any other fixed means (such as lines of rocks or marker stakes) for delineating preferred landing zones or maneuvering areas. Papillon has started operating to the site in 1997. Their annual passengers numbers to the site grew from 11,305 in 1999 to 77,742 in 2017, with just over 1 million passengers and 179,661 flights in total prior to the accident, the first near the site. The NTSB report that: The operator did not issue any written guidance to its pilots regarding specific approaches, approach profiles, or landing pads to use under certain conditions. The pilot (41 years old part-time employee with 2423 total flying hours, 1079 on type) had flown passengers into the Grand Canyon 836 times for Papillon Airways and made 581 landings at Quartermaster. Multiple Papillon pilots stated that the winds at Quartermaster were unpredictable and that the wind direction could drastically change during an approach into the landing site. A prior “urgent Weather Message” was issued by the National Weather Service (NWS) at 1008 that wind would increase in the late afternoon, peak overnight, and decrease the following morning. A Graphical Forecast for Aviation was issued about 1500 and valid for 1700 that depicted clear sky conditions, a surface visibility of greater than 5 statute miles, and northwesterly surface wind gusts between 20 and 35 kts in the accident region. At 1700, the Papillon [weather] station [2 miles NNW] reported wind from the NNW at 11 kts; at 1710, the wind was from the NNW at 11 kts gusting to 19 kts. At 1720, the wind was from the N at 11 kts, and at 1730, the wind was from the NNW at 12 kts, gusting to 24 kts. The company operations manual imposed maximum wind limitations of 30-35 kts steady wind and a gust spread of 20 kts or greater[sic]; these limitations applied to both on- and off- airport operations. Sunset was at 1711 and dusk was at 1738 [implying night flying to return]. The accident flight departed at 1642 Local Time, reached the Hoover Dam at about 1652 and entered the helicopter route “Green 4”. Radar coverage was lost at 1717, about 3.5 nm west of the accident site as the helicopter descended into the canyon. The operator had planned for 10 helicopters to arrive sequentially at Quartermaster. The accident pilot stated that, during the approach to Quartermaster, he noted that the eight helicopters that had already landed were facing in different directions, indicating variable...
read moreNZ Firefighting AS350 Accident: Role Equipment Design Issues
NZ Firefighting AS350 Accident: Weaknesses in Role Equipment Design and Distribution of Key Operating Data (Airbus AS350BA / FX2 ZK-HEX of Reid Helicopters Nelson) On 17 February 2019, a fire-fighting Airbus Helicopters AS350BA FX2 conversion (with a Honeywell LTS101-700D-2 engine), ZK-HEX of Reid Helicopters Nelson, suffered tail rotor damage and was forced to land in trees near Wakefield, Nelson, New Zealand. The sling for the underslung fire-fighting bucket contacted the tail rotor resulting in a loss of control. Investigators identified a vulnerability in the bucket’s design and shortcomings in promulgating essential design data to operators. The Accident Flight The New Zealand Transport Accident Investigation Commission (TAIC) explain in their safety investigation report that fires had been burning throughout the region over the preceding two weeks. ZK-HEX was one of several helicopters assisting using an external fire-fighting bucket, that TAIC refer to as a monsoon bucket. The [66 year old] pilot had been flying helicopters with monsoon buckets in fire-fighting operations since the mid-1970s [having 14,980 flying hours in total, c4,000 on type]. After dropping a load of water on the target area, the helicopter was returning to a nearby pond to refill the monsoon bucket. The pilot stated that while dipping the bucket normally into the dipping pond immediately before the accident the bucket “looked soft” and did not fill correctly. A second attempt was made to lower the bucket into the water, after which, the pilot observed, a weight of 800 kg displayed on the load cell. This confirmed to the pilot that the bucket was filled sufficiently. The pilot recalled the shape of the bucket looking normal and then continuing with the flight as intended. The pilot reported that after reaching cruise airspeed, the helicopter unexpectedly yawed violently one way and then the other. The pilot then heard a loud bang and the helicopter commenced an un-commanded turn to the left. The pilot initiated a descent for a forced landing, jettisoned the bucket and transmitted a Mayday radio call. The pilot descended towards an area of light bush close to a forest access road, but the helicopter started to spin near the ground. The pilot recalled following the recommended procedure for a loss of tail rotor control by closing the throttle, shutting the engine down to stop the helicopter spinning, and conducting an autorotative landing. A number of fire service personnel…arrived at the accident site within a few minutes and were able to assist the pilot out of the wreckage. The pilot received a minor ankle injury. The TAIC Safety Investigation TAIC does not appear to have any recorded flight data to examine. Examining the wreckage revealed: One tail rotor blade was broken at its root end but remained attached by its internal structure. The opposing tail rotor blade exhibited no external damage. The tail rotor drive shaft had failed at its forward coupling. The two pitch control links on the tail rotor assembly were found deformedand the tail rotor pitch-control slider had numerous indentations. Yellow synthetic [PVC] material was found on the tail rotor assembly at various locations. The same yellow material was also found on the leading edge of the broken tail rotor blade. The jettisoned bucket was found in a collapsed state in a forested area approximately 100 m to the south… A yellow synthetic sheathing was used to enclose the synthetic lifting line, electrical cable and pneumatic line. All of these exhibited damage...
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