Latent Engine Defect Downs R44: NR Dropped to Zero During Autorotation
Latent Engine Defect Downs R44: NR Dropped to Zero During Autorotation (R44 LN-OGF) On 23 March 2019 privately operated Robinson R44 helicopter LN-OGF crashed into trees during an attempted aurorotation after an engine power loss at Stavnes in Telemark, Norway. The Norwegian Safety Investigation Authority (NSIA) explain in their safety investigation report (issued 18 September 2020) that while en route at 1805 Local Time, the pilot… …noticed that he was losing engine power. An attempt to autorotate from an altitude of about 800 ft failed. The rotor stopped completely, and the helicopter dropped vertically along the trunk of a 30-metre fir tree. The branches cushioned the impact somewhat, but both people on board were severely injured and the helicopter destroyed. The Accident Flight and Precursor Events That Day The helicopter was privately owned and routinely rented out to private pilots. The NSIA investigation led them to examine an earlier flight that day. A pilot who had rented the [same] helicopter earlier that day…felt a thud in the helicopter during a slight climb, 3–4 minutes after take-off. He compared it to someone slapping the helicopter body with a flat hand. In retrospect, the first pilot could not say whether this affected the helicopter because he instinctively lowered the collective control lever and immediately started to turn the helicopter back 180°. All instruments showed normal values after the thud. During a slight descent on his way back to the farm, he felt another thud from the helicopter. It was weaker this time and he did still not register any instrument changes. Below was a suitable field for landing and he decided to go into autorotation and land the helicopter in the field. He then called the owner of the helicopter and explained the situation. Remarkably the pilot of this earlier flight did not have access to the aircraft technical log and so was unable to make an entry. Based on the various explanations, it is somewhat unclear to the NSIA what was said and understood by the various parties after this. The first pilot agreed with the owner of the helicopter that he would check the helicopter. If nothing obvious was detected, he would call the aircraft technician who performed maintenance on the helicopter. At the time, there was also telephone contact between the first pilot and the next pilot [the accident pilot, who NSIA refer to as the ‘commander’]. When the commander heard about the precautionary landing, he drove to the field. Together they checked the helicopter fairly thoroughly. Nothing unusual was detected. Again it appears nothing was entered in the technical log as the two pilots nor does NSIA explain what competence the two pilots had to conduct maintenance inspections. The first pilot contacted the aircraft technician at 1615 hours. According to the aircraft technician, the first pilot had explained that he had experienced a drop in rpm. The technician was busy and could not inspect the helicopter until the following day. He has explained to the NSIA that he “placed a flight ban on the helicopter.” He indicated that there might have been a problem with the freewheel, but other than that could not help establish what might have been wrong with the helicopter. However… The commander did not perceive that the aircraft technician or the owner had banned operation of the helicopter. He started the helicopter and lifted it into hover, while the first pilot was observing. The commander did not notice anything abnormal and after...
read moreFrozen Dash 8-100 Landing Gear After ‘Improper Maintenance Practices’ Say NTSB
Frozen Dash 8-100 Landing Gear After ‘Improper Maintenance Practices’ Say NTSB (Piedmont / US Airways Express Dash 8-100 N934HA at Newark) On 18 May 2013 Piedmont Airlines Bombardier DHC-8-102 / Dash 8-100, N934HA, operating as US Airways Express flight 4560, was forced to land with the landing gear retracted at Newark Liberty International Airport (EWR), New Jersey. The 34 people onboard were uninjured but the aircraft damage was classified as “substantial”. The US National Transportation Safety Board (NTSB) explain in their safety investigation report (issued 22 September 2020, 89 months later!) that: About 2325 [Local Time] , the flight was cleared for an instrument landing system (ILS) approach to runway 4R at EWR. When the crew attempted to lower the landing gear, the left MLG [Main Landing Gear] showed a red unsafe indication in the cockpit. The captain received approval from an EWR air traffic control tower controller to perform a “fly-by”; the tower confirmed that the left MLG appeared to be partially extended. The crew put the aircraft in a holding pattern at 3000 ft, completed the appropriate checklists and liaised with the airline’s duty maintenance control supervisor by radio. Their troubleshooting did not succeed. When the fuel remaining was 900 lbs, the captain decided to make an emergency landing with all landing gear retracted, and the maintenance personnel agreed. The captain made a passenger address announcement, briefed the FO on the planned landing, and called for the emergency landing checklist. In accordance with the checklist, he pulled the B3 GPWS circuit breaker (CB). The captain flew the ILS approach to runway 4L. The landing gear warning horn did sound during the approach. The First Officer described it as “extremely distracting”. The airplane landed [at 0104 Local Time] about 3,000 ft down the runway and slid about 2,000 ft, stopping on the runway centerline in a wings-level attitude. An evacuation was conducted through the forward doors without injury. The NTSB Safety Investigation The NTSB explain that both flight crew had reported for duty at 1255. The captain was undertaking his 6th sector of the day. Both reported they were well rested before reporting for duty and were “not affected by fatigue or other personal issues”. Bombardier Quick Reference Handbook (QRH) does also call for the CB for the horn be pulled before any gear up landing. When the FO was asked if he read the entire checklist, including the warnings, cautions and notes, he stated he got distracted because the checklist said “verify three green lights illuminated.” The three lights were not there, and there was nowhere to go from there. At that point he was unsure about reading the rest of the checklist. Examination of the MLG showed that… …neither landing gear displayed visible physical damage. However, the left MLG uplock roller was found seized and would not rotate by hand. The right MLG uplock roller could be rotated by hand. On the latch of both the left and right MLG uplocks, a “worn” groove was noted on the lower surface of the latch. The groove in the left uplock latch appeared slightly larger than the groove in the right uplock latch. The grooves on the left and right uplock latch were measured. A comparison of the measurements of the grooves against the landing gear manufacturer’s specifications showed that the groove on the left MLG uplock latch was at or beyond wear limits,...
read moreInvestigators Suggest Cultural Indifference to Checklist Use a Factor in TAROM ATR42 Runway Excursion
Investigators Suggest Cultural Indifference to Checklist Use a Factor in TAROM ATR42 Runway Excursion (YR-ATB, Moldova) On 4 June 2017 TAROM ATR 42-500 YR-ATB suffered a runway excursion on landing at Chisinau airport, Moldova. The authorities of the Republic of Moldova delegated the investigation to the Romanian Civil Aviation Safety Investigation and Analysis Authority (AIAS). AIAS explain in their safety investigation report (issued on 30 September 2020) that the approach was to be performed by the First Officer, as the Pilot Flying (PF), however the Aircraft Commander was required by SOPs to take control at 70 knots for braking and steering the aircraft. During the ILS approach to runway 08 the aircraft was configured with flaps 35º, was stabilized, maintaining an indicated speed between 114 – 120 kt. To counteract the lateral wind influence [13-22 knots], the crew operated the control column and the rudder to keep the aircraft stabilized on the localizer (runway heading), respectively the aileron input into the wind to cancel the wind influence and the rudder to the left to control yaw and to keep the aircraft on the runway axis. …at 15:11:47 the aircraft touched down the runway on both main landing gears. [However], the aircraft did not maintain the runaway centreline, and made a runway excursion on the right side. After a roll of about 90 m on the grass, the crew managed to put the aircraft on the concrete surface of the runway by using the aircraft’s control surfaces (rudder and ailerons) and applying a differentiated thrust of the engines (left engine in Ground Idle and right engine in Flight Idle). When the aircraft re-entered on the concrete surface of the runway, it hit the concrete base of a beacon located on the runway edge with the main landing gear’s wheels. The aircraft made a sharp turn to the left, crossed the runway and exited on the opposite side… …stopping with the landing gear on the grassy surface on the edge of the runway. The occupants were uninjured. The landing gear, wheels, brakes and tyres had to be replaced. AIAS Safety Investigation / Analysis The investigators created a reconstruction video: They concluded that after touch down the rudder inputs were too extreme… …ranging from maximum left to maximum right. Within 15 seconds the rudder was actuated to maximum values three times in a row (left 4 s – right 3 s – left 8 s). The rudder pedal controls are initially used to keep the aircraft on the runway axis and any deviation must be corrected by smoothly amplitude inputs. Overcorrections can cause oscillations of the aircraft’s ground trajectory, which can lead to loss of control during roll. [Furthermore]…the crew did not use the steering system or the aircraft’s braking system, which contributed to the partial loss of aircraft control during rolling. By analyzing the conversations between the pilots recorded by CVR, the investigation commission concluded that there was a moment of uncertainty, immediately after the aircraft touched down the runway, related to whom had the aircraft control (the First Officer to the pilot in command “Yours, yes?”, [the pilot in command responsed “What?”]). They also observer that: In practice, First Officers, even when they are PFs, do not operate the aircraft’s brakes after touchdown, the braking being done exclusively by the pilot in command. This practice is...
read moreHelideck Lightning Strike: Damage Missed
Helideck Lightning Strike: Damage Missed On 8 August 2019 the pilot of an Airbus Helicopters AS350B2 had shut down and tied down on a Gulf of Mexico (GOM) offshore installation, EI-333B, as a storm approached. The helicopter was on charter to the Bureau of Safety and Environmental Enforcement (BSEE) to ferry inspectors to offshore installations. A second helicopter from another company was landing to also take shelter when a lightning strike occurred that set off one of the installation’s alarms. The pilot of the AS350B2 commented: I had intended to go up and help him tie down. However, as I was getting ready to walk out the door, the bolt that set off the platform alarm hit and I decided to stay indoors. The other pilot came in shortly after and said he was pretty sure the platform had just been hit by lighting. After the storm passed, I went up stairs and looked over my aircraft. I didn’t see any obvious damage to the outside of the aircraft. I proceeded to turn on the Battery, avionics, and all exterior lights. All systems were functioning properly. After the inspectors returned to the platform, we departed and returned to Lafayette with no incident. Startup was normal with no indications of anything out of the ordinary. Upon return to Abbeville, I did inform the Lead Mechanic that lighting had stroke the platform. I told him that I had looked over the aircraft, but that on the post flight, he may want to take a close look at the aircraft. On inspection at Abbeville maintenance personnel found damage to the top of the vertical fin (Figure 1), the aft strut (Figure 2), and the bottom of one skid (Figure 3). Illustrations Credit: BSEE. This occurrence report highlights the need to carefully inspect for damage when a lightning strike was possible, even when the aircraft was parked. The main danger of lightning strikes is the arcing damage they can do to rotors, transmissions and engines. Other Helideck Safety Resources Helideck Safety Alerts: Refuelling Hoses and Obstructions NTSB Recommendations on Offshore Gas Venting Mind the Handrail! – Walk-to-Work Helideck Hazard Passive Fire-Retarding Helideck Designs US BSEE Helideck A-NPR / Bell 430 Tail Strike Troublesome Tiedowns Helideck and Helicopter Egress Training Facilities Wrong Deck Landings FOD and an AS350B3 Accident Landing on a Yacht in Bergen UPDATE 16 April 2022: Helideck Heave Ho! Aerossurance regularly assists oil and gas companies and vessel operators review and update their helideck procedures and adverse weather policies, examine helideck structural integrity issues and provide independent assurance of helideck readiness. Aerossurance has extensive air safety, operations, helidecks, 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 moreFatal Fatigue: US Night Air Ambulance Helicopter LOC-I Accident
Fatal Fatigue: US Night Air Ambulance Helicopter Loss of Control – In-flight Accident (Air Methods AS350B2 N127LN, Wisconsin) On 26 April 2018 Air Methods Corporation (AMC) Airbus Helicopter AS350B2 air ambulance helicopter N127LN was destroyed in a Loss of Control – In-flight (LOC-I) accident near Hazelhurst, Wisconsin. The pilot and two medical personnel aboard were fatally injured. The helicopter, operating as ‘Ascension Spirit Air‘, was on a night repositioning flight after two prior inter-hospital patient transfer flights with a refuelling stop. The US National Transportation Safety Board (NTSB) has issued a simple probable cause: The pilot’s loss of helicopter control as a result of fatigue during cruise flight at night. The Final Flights and the Pilot’s Immediate History The NTSB explain in their safety investigation report (issued 23 September 2020) that… The accident flight was the [34 year old] pilot’s first flight after a week-long family vacation in Florida. …the pilot had a sleep opportunity of more than 9 hours during each of the 6 nights before the accident. The trip [home the day before]…involved [a flight, a 4 hour drive and] a change in time zones. AMC pilots work 12-hour shifts, with a 7 days on and 7 days off, then 7 nights on and 7 nights off pattern. In this case the pilot was resuming the roster with a night shift. The pilot’s wife reported no issues with the pilot falling asleep or staying asleep. The pilot’s wife thought that he went to sleep between about 2100 and 2130. The time that the pilot awoke on the day of the accident was not known. The pilot’s wife stated that, before going on duty, he would normally rest and sleep during the day… The pilot’s wife had also been an AMC pilot for 10 years and was then a pilot at the same base. She was resuming the roster with a day shift and the implication was she had left home before her husband awoke. Contemporary press reports suggest the family had two young daughters. It is explained that the pilot: …took the kids to daycare so that he could rest for his night shift. He went to the grocery store in the morning and then went home to rest. At about 4:00PM he took his daughter to a doctor’s appointment. She saw her husband when he arrived at work for the night shift and thought that he had arrived about 45 minutes early for his shift. He arrived early because he was already in town for the doctor’s appointment and his wife had turned down the flight to Madison, Wisconsin (see below) for duty time reasons. They did the shift change together, and she noted nothing unusual about her husband. Cellular telephone records indicated his activity from 0725 to 2057 with three extended breaks in activity (greater than 60 minutes) from 0923 to 1118, 1431 to 1556, and 1741 to 2040. Of these three periods the first could overlap with the grocery shopping and the third does overlap with flying (see below). Beyond one witness statement and analysis of phone records the NTSB human factors analysis does not reconstruct the pilot’s daytime activities further. The NTSB explain the helicopter and crew had… …transported a patient from the Howard Young Medical Center Heliport (60WI), Woodruff, Wisconsin, to the Merrill Municipal Airport (RRL), Merrill, Wisconsin, departing about 1759 and arriving about 1819. The helicopter...
read moreCrossing Cable Wirestrike
Crossing Cable Wirestrike (JSHS MD369D F-GJLX) On 16 October 2019 Jet Systems Helicopters Services (JSHS) Hughes / MD 369D (500D) F-GJLX was conducting an inspection of medium voltage electric power lines near Blancey for utility company Enedis (part of EDF) when it suffered a wire strike with a crossing high voltage cable. The French Bureau d’Enquêtes et d’Analyses pour la Sécurité de l’Aviation Civile (the BEA) explain in their safety investigation report (issued 18 September 2020 in French) that it was late afternoon and a team of 3 (a pilot, a systems operator in the front right seat from specialist company Visimind and a technical observer in the rear right seat) were making their third flight of the day. The pilot… …had a total experience of 2,862 flight hours including 168 on the Hughes 500. He had started surveillance missions in April 2019 and had a total of 300 flight hours in this area. The systems operator had started training in October 2018 when he was recruited. He also completed a 5-day training course at JSHS in January 2019, leading to a practical exam and a certificate issued by Enedis. He had a total of 150 hours experience with the Hughes 500 and Robinson R44. The technical observer had 1,200 hours of experience, including 800 on the Hughes 500. They were using both a camera and LIDAR to survey vegetation surrounding the power line. Such operations are usually conducted offset to the left of the cable, c15-50 ft above at very low speed (just c 10-30 knots). Unlike the other 369D in JSHS’ fleet, F-GJLX was not fitted with a wire strike protection system (WSPS). The pre-flight briefing…(as well as the entire mission) was carried out in English because the systems operator was of Polish nationality. Although the trio had not flown together before they reported no problems of comprehension. The technical observer did comment however that there was less dialogue that normal though between pilot and systems operator (who was effectively the navigator for this type of task). The crew planned the mission by also taking into account Enedis’ recommendation to limit themselves to a maximum of six flight hours per day. The briefing was conducted with a map in order to decide on the route and to visualize the various obstacles. The systems operator proposed a route, which the captain asked to do in the opposite direction to better take into account the meteorological situation over the entire trip (sunshine, cloudiness, wind). Although the aircraft maintained a safe distance from the power line being inspected (shown in blue below) its main rotor struck a perpendicular crossing power line (shown in orange). The pilot did not see the line before hitting it, due to a low contrast between the High Tension line and the surrounding space making it difficult to detect cables and an absence of metal support in his field of vision. On the section of line inspected during the collision, the sun was slightly head-on but not dazzling. The pilot made a precautionary landing 20 seconds later. The canopy was damaged and there was also electrical arcing damage. The crew demonstrated excellent teamwork by holding an immediate hot debrief. The crew observed that although the crossing cable was charted the mapping system (shown below) the system was zoomed in on the cable being inspected (shown in blue) and so the crossing cable (in red)...
read moreHanging on the Telephone… HEMS Wirestrike
Hanging on the Telephone… HEMS Wirestrike (Rega Airbus H145 HB-ZQM) On 1 August 2019 Rega HEMS Airbus Helicopters H145 (BK117D2) HB-ZQM departed the Rega base in St. Gallen at 1830 for a tasking in Walzenhausen on the Austrian border. On board were a pilot, a paramedic / Technical Crew Member (TCM) and doctor. History of the Flight The Swiss Safety Investigation Board (SUST) explain in their safety investigation report (issued 24 August 2020 in German) that: During the flight, the pilot and the TCM analysed the obstacle situation at the planned location with the help of the on-board navigation device and the Electronic Flight Bag (EFB). They registered electricity and telephone lines that reached a height of less than 25 m above ground. An employee of the ground-based rescue service was at the scene and instructed the crew on the landing. During the approach, which took place in the direction of a fork in the road (see point 1), the crew sighted the telephone line. When the helicopter was on its final approach, the rotor downdraft (downwash) the lid of a grit container… The crew noticed this, whereupon the pilot aborted the approach and started a slow reverse flight. He then hovered the helicopter at a safe distance until the rescue worker on the ground, who had been informed accordingly by the pilot via radio, had secured the lid. In this phase, the pilot assessed the cable situation at the slightly higher road curve (see point 2) and came to the conclusion that the telephone line seemed to span the meadow diagonally behind the curve. The second approach then took place at the fork in the road (point 1). The pilot briefly touched down the helicopter on the road, but found that the landing area was too steep and that the helicopter had therefore tilted too far back around its transverse axis to be able to switch off the engines. He immediately took off the helicopter and headed for the slightly higher road curve (point 2), where the road was a little less inclined. During this maneuver, the TCM observed the slope rising to the left of the helicopter as well the display of the rear view camera on the multifunction screen. Shortly before touchdown, in the direction of flight of the helicopter, a main rotor blade touched the telephone line running across the curve of the road, whereupon it was cut. The doctor who was sitting in the cabin noticed this at the same time as the pilot, who at that moment saw a black cable in front of him in the lower right corner. Since the pilot noticed neither vibrations nor any impairment of the control system, he flew the helicopter to an open landing site in the Rhine plain about 1.4 km to the northwest and landed there without any further incident. The Safety Investigation and Analysis Examination of the helicopter revealed “traces of wear from black rubber” near the tip of a main rotor blade. There was no evidence of blade structural damage or any other damage to the helicopter. The helicopter was released to service subsequently. The investigators note that: Telephone lines, which often run parallel to streets in order to simplify maintenance work on the line, generally do not reach a height of 25 m above ground. For this reason, such lines are not entered in the official and generally...
read moreGust Lock Gaff: King Air A90 Runway Excursion
Gust Lock Gaff: King Air A90 Runway Excursion On 23 June 2016 a Beechcraft King Air A90 aerial survey aircraft suffered a runway excursion during a take off attempt at Hannover Airport. The German Federal Bureau of Aircraft Accident Investigation (BFU) explain in their safety investigation report (dated 10 March 2020, but issued August 2020) explain that the Belgian owned aircraft, whose registration is not recorded by the BFU, was chartered to a Danish aerial survey company. Onboard that day were a pilot and a camera system operator. During taxi the pilot had noted it was “unusually difficult to control the direction of the aircraft” but not so bad as to cause concern. At about 0828 hrs, the pilot received the clearance from the tower controller to enter runway 09L. He stated that about 1 min later he received take-off clearance and set engine takeoff power. He had paid attention to the two engines building up their take-off rotation speed uniformly. During the take-off run he had noticed a change in direction towards the left and tried to keep the aircraft on the runway centreline by using the right rudder pedal. He had pushed it up to the mechanical stop. The mounting of the right rudder pedal fractured in the process. The aircraft could no longer be controlled. It veered left off runway 09L with a speed of about 30 kt… It came to a stop on the grass next to the runway. [The aircraft] had yawed by approximately 70°. The Safety Investigation The King Air A90 has a Gust Lock System for use if the aircraft is parked for longer periods of time to prevent damage to the control surfaces due to movements caused by wind. The Pilot Operating Handbook says: Positive locking of the rudder, elevator and aileron control surfaces, and engine controls (power levers, propeller levers, and condition levers) is provided by a removable lock assembly consisting of two pins and an elongated U-shaped strap interconnected by a chain. Installation of the control locks is accomplished by inserting the strap over the aligned engine control levers from the copilot’s side; then the aileron-elevator locking pin is inserted through a guide hole in the top of the pilot’s control column assembly, thus locking the control wheels. The rudder pedals are held in the neutral position by the largest of the two pins, which is installed horizontally through the pilot’s rudder pedals. Removal sequence is a reverse of the installation procedure. […] Caution Do not tow aircraft with rudder locks installed, as severe damage to the nose steering linkage can result. […] The manufacture claim that these “…lock a combination of primary flight controls in positions that will preclude taxi…”. The BFU note that (our emphasis added): In the aircraft concerned the safety chain, which normally runs from the control column to the power lever to the pedals was missing. There was no warning flag on the safety pin for the rudder pedals. The original red paint was barely visible. The A90 pre-flight checklist includes: (2) removal of control locks (but doesn’t specify how many), (11) checking propeller control movement and (14) the flying control ‘Free & Correct Movement’ check, verifying the control surface movement including their correct deflections. To complete (11) and (14) the locks have to been removed. The BFU note that also: After engine start-up, the Before Taxi Checklist listed the item Flight Controls –...
read moreHawaiian Air Tour EC130T2 Hard Landing after Power Loss (Part 1)
Hawaiian Air Tour EC130T2 Hard Landing after Power Loss – Part 1 (Blue Hawaiian N11VQ Kauai) On 17 January 2016 Airbus Helicopters EC130T2 N11VQ, operated by Blue Hawaiian Helicopters (an Air Methods subsidiary), crashed near Hanalei, Kauai, Hawaii during a Part 135 air tour flight. The pilot and six passengers were all seriously injured. In this, the first of two articles, we look on why the helicopter crashed. Part 2 looks at the survivability issues. It is estimated that the initial impact was 24g in the vertical axis, 9g in the horizontal axis, and 4g in the lateral axis. The helicopter bounced and then impacted at 19g vertically, 7g horizontally, and 1 g laterally. The Accident Flight The US National Transportation Safety Board (NTSB) explain in their safety investigation report (issued 25 August 2020): The pilot reported that, about 25 minutes after departure for the sightseeing flight, the helicopter was about 1/4-mile offshore NW of the Honopu Sea Arch between 1,300 ft and 1,400 ft mean sea level (msl) when he heard the low rotor rpm aural warning horn. NTSB comment that: The first indication of an inflight loss of power was an uncommanded right yaw that occurred at 14:31:31. The first limit indicator (FLI) on the instrument console started to drop rapidly, followed by the GENE (generator) annunciator light illumination. The EC130T2 is powered by a Safran Arriel 2D turboshaft engine with a dual channel FADEC. The pilot entered an autorotation, initiated a 20° right turn turned toward shore and made a distress call. Five seconds later, the ENG P (engine oil pressure) annunciator light illuminated, followed by the FUEL P (fuel pressure) light and the helicopter returned to a nearly-level flight attitude. About 10 seconds later, the helicopter was passing through 600 ft at 85 knots. Rotor rpm had increased to 430. After about 11 seconds, the coastline became discernable and revealed a rocky, unsuitable landing area. The helicopter’s altitude was about 350 ft and the rotor speed was 364 rpm. At 14:32:08, the helicopter had entered a 45° right bank, altitude was 275 ft, airspeed was zero, and the helicopter was maneuvering toward a sandy beach area. About 3 seconds later, the LIMIT (servo limit) light illuminated, the helicopter entered a near-level pitch attitude, airspeed was near zero, and rotor speed was around 200 rpm. Initial ground impact was at 14:32:13 and the rotorcraft was at rest at 14:32:15. [The pilot] applied the rotor brake to slow the rotor and noted that the engine was not running. The passengers began to exit the helicopter and he pulled the engine fuel cutoff. Six of the seven helicopter occupants were diagnosed on the day of the accident with thoracolumbar compression fractures. The seventh was diagnosed several weeks later. With the exception of the occupant of seat No. 1 (who became paraplegic), the occupants remained neurologically intact. NTSB Safety Investigation Examination of the engine revealed that the main fuel injection pipe between the fuel valve assembly and the injection union was cracked and broken at the injection union B-nut connection. A close view of the fracture surface on the tube portion revealed fractographic ratchet marks and crack arrest marks consistent with reverse bending fatigue fracture initiation at two diametrically opposite positions on the outside surface of the tube. [This] allowed pressurized fuel to escape, reducing fuel flow and pressure to...
read moreAir Ambulance Helicopter Downed by Fencing FOD
Air Ambulance Helicopter Downed by Fencing (Metro Aviation Airbus BK117C2 / H145 N263MH) On 4 July 2020 Metro Aviation air ambulance Airbus Helicopters BK117C2 / H145 N263MH was involved in an accident at Wayne County Airport (KBJJ), Wooster, Ohio. The US National Transportation Safety Board (NTSB) explain in their preliminary report that: Surveillance video showed that after lifting off a portable dolly [at c 1357 Local Time], the helicopter…turned right and briefly hovered. As the helicopter began to take off following the hover, it traversed a grassy area adjacent to the ramp about 10 ft above ground level (AGL), where a silt construction fence was obscured by tall grass. As the helicopter overflew, the fence became unsecured and blew up and into the main and tail rotor system. The crew then performed a forced landing, which resulted in substantial damage to the fuselage, tailboom, and tail rotor blades. The two pilots, flight nurse and flight paramedic were uninjured. At the time of the accident, there were no notices to airmen (NOTAMs) for the construction fence and the presence of the fence was not contained within any publications or notices available to pilots. UPDATE 23 February 2022: Extra information is released in the NTSB Public Docket: According to the pilots, the construction in the area of the fencing had started about 2 months prior to the accident and that coincided with the installation of the fence. One of the pilots stated that he had inspected the fence himself and remembered the bottom being buried in the ground about 4 to 6 inches and attached to wooden stakes with staples and nails. He said, regarding the silt fence, that he “never imagined it would come out at that altitude.” The second pilot stated: …he did not remember seeing the construction fencing prior to the accident, but he had flown over that area many times, he just did not take notice of it as a factor. He stated that upon liftoff and forward movement, he saw it balloon a split second before it blew up into the air and became tangled in the blades. He stated that orange barriers are also located on the airport that would normally be filled with water, but they would leak and blow around, which is why they elected to fly over the grass. UPDATE 18 March 2022: NTSB Probable Cause The NTSB Probable Cause is a rather bland and simplistic statement of the circumstances of the accident: The entanglement of construction fencing into the main rotor system, which necessitated a forced landing that resulted in substantial damage to the helicopter. Operators Safety Actions The operator stated they had done the following: Safety Resources FOD and an AS350B3 Accident Landing on a Yacht in Bergen Impromptu Landing – Unseen Cable Pilot Goose(d) Surprised and Crashed Rotor Blade Tool Control FOD Incident Ambulance / Air Ambulance Collision S-92A Collision with Obstacle while Taxying Helideck Safety Alerts: Refuelling Hoses and Obstructions UPDATE 13 September 2020: Hawaiian Air Tour EC130T2 Hard Landing after Power Loss (Part 1) UPDATE 20 September 2020: Hanging on the Telephone… HEMS Wirestrike UPDATE 19 December 2020: Helicopter Destroyed in Hover Taxi Accident UPDATE 23 January 2021: US Air Ambulance Near Miss with Zip Wire and High ROD Impact at High Density Altitude UPDATE 31 January 2021: Fatal US Helicopter Air Ambulance Accident: One Engine was Failing but Serviceable Engine Shutdown UPDATE 13 March 2021: S-76A++ Rotor Brake...
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