SAR Crew With High Workload Land Wheels Up on Beach
SAR Crew With High Workload Land Wheels Up on Beach On 9 August 2016, a Search and Rescue (SAR) Leonardo AW139 of the Japan Coast Guard (JCG), JA968A, made a wheels-up landing on a beach in Miyagi Prefecture, Japan. The aircraft had been called out on a rescue mission in a small cove in the wake of a passing tropical storm. History of the Flight According to the Japan Transport Safety Board (JTSB) safety investigation report, as the aircraft was descending through 150ft on approach to enter a hover in the cove, the aural warning that the landing gear was still up sounded. The aircraft commander requested that the co-pilot cancel the alert. At the same time the aircraft was experiencing considerable turbulence and the Aircraft Commander was cautious to avoid an over torque. The crew successfully winched two survivors aboard and it was decided to land on the adjacent beach to pass the casualties to a shore party. The beach was sloping and their was a risk of debris and so the crew were attentive to those hazards, however the pre-landing checklist does not appear to have been followed according to the JTSB. On landing…well you may have guessed…the pilot realised that his eye line was lower than usual… Having landed wheel up, the Aircraft Commander, then lifted the helicopter, lowered the gear and landed again. The aircraft, which did have a mechanic onboard, was subsequently flow back to Sendai Airport. The aircraft had suffered damage to the lower fuselage, namely: Deformed outer skin panel, deformed frame at the fuselage bottom and the damaged Heli-Tele antenna VHF 2 antenna damaged upper cover of the hoist light collapsed and deformed Search light glass cracked JTSB make no comment on why the JCG unusually do hoisting wheels up. JTSB Probable Cause …the Rotorcraft suffered damages because it had landed without extending the landing gear. Regarding why it had landed without extending the landing gear, it is probable that various tasks were occurred in short time span and at same time other crews on board were also focusing on their own various tasks, so that they could not carry out necessary corporation or support, and because the workload of the captain continued to be high, there were not enough time for the captain to shift his mind from the rescue operation to the landing procedure, as the result, he forgot the check prior to the landing prescribed in the flight manual and did not check the landing gear condition. Safety Actions JCG actions included: Re-educating, re-training and examining flight for captains and co-pilots; Re-education of Sendai Air Base personnel on the implementation of Crew Resource Management (CRM) Emphasising the application of checklists and briefings Continuations of periodic CRM training and sharing the contents of each flight debriefing systematically to utilize those for practical CRM education Emphasising compliance with Operating Manual and the division of crew roles Continuation of safety audits Dynamic risk assessment of landing sites Safety Resources You may also be interested in these Aerossurance articles: James Reason’s 12 Principles of Error Management Back to the Future: Error Management Complacency: A Useful Concept in Safety Investigations? HROs and Safety Mindfulness Business Aviation Compliance With Pre Take-off Flight Control Checks Investigation into F-22A Take Off Accident Highlights a Cultural Issue C-130J Control Restriction Accident, Jalalabad HF Lessons from an AS365N3+ Gear Up Landing Korean T-50 Accident at Singapore...
read moreInvestigation into F-22A Take Off Accident Highlights a Cultural Issue
Investigation into F-22A Take Off Accident Highlights a Cultural Issue: 07-4146 at NAS Fallon, 13 April 2018 On 15 November 2018 the US Air Force (USAF) released the Accident Investigation Board (AIB) report into a Lockheed Martin F-22A Raptor 07-4146 accident at NAS Fallon, NV on 13 April 2018. The Accident Flight The F-22A of the 90th Fighter Squadron, based at Elmendorf-Richardson, Alaska, was taking off from Fallon for a Top Gun graduation exercise, operating against US Navy F-18s. The aircraft was rotated at 120 knots calibrated airspeed (KCAS) and the pilot subsequently raised the landing gear handle (LGH) to retract the landing gear (LG) on sensing the aircraft becoming airborne. However, just after the main landing gear (MLG) retracted, the aircraft settled back on the runway. The MLG doors were shut but the nose landing gear (NLG) doors were still in transit. The aircraft slid over 6,500 ft (1985m), stopping 9,400 ft (2,865m) from the runway threshold. The pilot was uninjured. Early reports of an engine malfunction, possibly based on engine nozzle positions, proved false (the nozzles free float in an in-flight shut down and in this case when weight on wheels was not activated). The Investigation The investigators make much of the fact that Takeoff and Landing Data (TOLD) was not calculated for the conditions that day at NAS Fallon as required. Consequently, the TOLD on the pilot’s lineup card was based on a… …a military power (MIL) takeoff at 80 degrees Fahrenheit (F) using a 10,000 ft runway at sea level. The elevation of NAS Fallon is 3,934 ft, runway 31L is 13,961 ft long, and the temperature on the morning of the mishap was 46 degrees F. The rotation and takeoff speeds listed on the lineup card were 136 KCAS and 163 KCAS respectively. The calculated rotation and takeoff speeds for the conditions at NAS Fallon on the day of the mishap are 143 KCAS and 164 KCAS respectively. The pilot based his decision on whether the aircraft was airborne on peripheral vision only. without verifying the climb dive marker (CDM) was above the horizon or the vertical velocity indicator (VVI) was positive. In fact, the pilot had initiated rotation at just 120 KCAS. This was 16 knots below the line up card and 23 knots below a correctly calculated rotation speed. Weight off wheels occurred at at 135 KCAS. This was 28 knots below the line up card and 29 knots below a correctly calculated take off speed. The F-22A momentarily became airborne, but there was insufficient lift to sustain flight. Data from five past sorties showed that this pilot initiated rotation at 120±5 KCAS. The pliot stated: There is a technique that I heard from somewhere (I don’t know where, whether it was at the B-Course [the type conversion course] or [at his squadron,] the 90th) to initiate [rotation] – if you have a 136 [rotation speed], kind of standard below 2,000 feet – that you initiate aft stick pressure at 120 so that the nose is up at that rotation speed, and that has been my habit pattern. This technique was not limited to one pilot. In 64.3% of 56 sorties sampled, rotation was initiated greater than 5 knots prior to the calculated rotation speed and in 52.1%, rotation occurs at 120±5 KCAS (as per the accident pilot). All pilots who were interviewed noted that they check their TOLD before takeoff. After the mishap, at a pilot meeting attended by 20 to 30 F-22 pilots, about...
read moreInadequate Maintenance, An Engine Failure and Mishandling: Crash of a USAF WC-130H
Inadequate Maintenance, An Engine Failure and Mishandling: Crash of USAF WC-130H 65-0968 in Savannah, Georgia On 2 May 2018, a Lockheed WC-130H Hercules, 65-0968, of the Puerto Rico Air National Guard‘s 156th Airlift Wing (156 AW), crashed shortly after take off from Savannah/Hilton Head International Airport (KSAV), Georgia. All nine persons on board were killed. The last moments of the flight were captured on dramatic CCTV footage: History of the Accident Flight The aircraft was en route to Davis-Monthan Air Force Base, Arizona (commonly known as ‘the boneyard‘) to be retired. It had however been at been at Savannah/Hilton Head since 9 April 2018 for scheduled fuel cell maintenance which could not be done in Puerto Rico due the unit’s hangar being damaged by Hurricane Maria in September 2017. Unscheduled work on engine no 1 had also been conducted (see below). The aircraft commander, Mishap Pilot 1 (MP1), had 18 years or service, was an instructor pilot and was “regarded by many as the best pilot in the unit” according to the US Air Force (USAF) Accident Investigation Board (AIB) report. The AIB say that the crew performed a rolling take off that morning, and so were less able to check for correct engine performance. During takeoff roll, engine one revolutions per minute (RPM) fluctuated and did not provide normal RPM when MP1 advanced the throttle lever into the flight range for takeoff. At approximately eight seconds prior to aircraft rotation, the engine one RPM and torque began to significantly decay and dropped to 65% RPM and 1,971 in-lbs torque at the moment of rotation. [The Mishap Flight Engineer] MFE failed to execute his learned and practiced visual scan patterns to recognize the loss of power and call for a reject of the takeoff. The fluctuation on roll and significant performance decay went unrecognized by the MC [Mission Crew] until rotation, when MP1 commented on aircraft control challenges and the MA [Mishap Aircraft] veered left and nearly departed the runway into the grass before it achieved flight. As the landing gear, was retracted the crew identified the engine no 1 malfunction and MP1 called for engine shutdown. However, the investigators say the crew… …failed to complete the Takeoff Continued After Engine Failure procedure, the Engine Shutdown procedure, and the After Takeoff checklist as directed by the Flight Manual, and the MA’s flaps remained at 50 percent. Additionally, MP1 banked left into the inoperative engine, continued to climb, and varied left and right rudder inputs. At an altitude of approximately 900 feet mean sea level and 131 knots indicated air speed, MP1 input over nine degrees of left rudder, the MA skidded left, the left wing stalled, and the MA departed controlled flight and impacted the terrain on Georgia State Highway 21. Previous Flight, Maintenance Troubleshooting and Engine Failure Analysis On the ferry flight from Puerto Rico to Savannah [on 9 April 2018], the flight crew…experienced an RPM issue with engine one, and reported the incident for troubleshooting and repair. The crew explained in the write up that engine one’s RPM dropped to 96% when the crew switched the synchrophaser master switch off during final approach (a step taken as the aircraft is on approach for landing). However, as explained in the write up, the ferry crew believed the RPM corrected to normal parameters when they switched on the propeller governor control to mechanical governing. Upon landing...
read moreLost Tool FODs Propeller Blade, Penetrating Turboprop’s Fuselage
Lost Tool FODs Propeller Blade, Penetrating Turboprop’s Fuselage (SA226 N158WA) On 20 March 2017, during a pre-dawn take off for a single pilot positioning flight from Boise Air Terminal/Gowen Field (BOI), Idaho, Western Airlines Swearingen SA226TC Metro II N158WA suffered substantial foreign object damage due to a forgotten tool. Accident Flight According to the safety investigation report from the US National Transportation Safety Board (NTSB): …the pilot reported that prior to departing on the repositioning flight, he reviewed the maintenance data [sic] and found everything to be up to date. The subsequent preflight inspections, inclusive of the interior and exterior of the airplane revealed no anomalies. The pilot stated that at 0400 he called BOI ground control, obtained taxi clearance, and taxied to runway 10L where he began the takeoff roll. The pilot reported that everything was normal, rotated at 105 knots; shortly thereafter he heard a “pop”, followed by a vibration. Thinking that he had a blown tire, he waited a few seconds to see if the frequency of the vibration would change as the tire rotation slowed. However, the vibration remained the same, which led him to think that there might be an issue with the propeller. The pilot radioed the BOI tower controller, advised him of his intension to return to the airport… The pilot stated that on the downwind leg he thought there might be a problem with a propeller. The pilot then landed uneventfully, taxied to parking, and shut the right engine down first. The pilot then shut the left engine down. During the last few rotations of the propeller he observed the spinner wobble slightly; he then noticed that the tip of one of the blades was missing. About four inches (100 mm) of one blade was missing and there were three holes in the fuselage. Two piece of blade debris was found in the aircraft and the arm rest on the jump seat was also damaged. Airport operations personnel recovered another piece of propeller blade debris from the runway and “what appeared to be the blade of a screwdriver and two pieces of a screwdriver handle”. Investigation A Federal Aviation Administration (FAA) inspector reported to the NTSB that maintenance had been performed on the aircraft prior to that flight, and… …the mechanic was called away from the task he was performing prior to it being completed. The inspector stated that a screwdriver was left on the nose of the airplane under the windshield wiper and out of sight of the pilot. Subsequently, on takeoff roll the screwdriver became dislodged and impacted the left propeller. Disappointingly, the NTSB investigation reveals no further information on the circumstances of this uncompleted maintenance or the tool control procedures that were in use. Safety Resources We have previously discussed good practice in control tool in: Rotor Blade Tool Control FOD Incident Aerossurance has previously also published these articles that should be of interest: Professor James Reason’s 12 Principles of Error Management How To Develop Your Organisation’s Safety Culture Maintenance Human Factors: The Next Generation Aircraft Maintenance: Going for Gold? Nose Gear Collapse Filmed By FOD Detection System (Beechcraft Queen Air 4X-DZY) Rotor Blade Tool Control FOD Incident FOD and an AS350B3 Accident Landing on a Yacht in Bergen Micro FOD: Cessna 208B Grand Caravan Engine Failure & Forced Landing FOD Damages 737 Flying Controls Crew...
read moreKorean T-50 Accident at Singapore Airshow
Korean T-50 Accident at Singapore Airshow On 6 February 2018 a KAI T-50 Golden Eagle trainer of the Republic of Korea Air Force (ROKAF) suffered a runway excursion and overturned during a formation take off at the Singapore Airshow. History of the Flight The T-50 veered to the right of Runway 20R in Changi Airport during take-off for an aerial display with 7 other T-50s of the ROKAF flying display team. Subsequently, the aircraft zigzagged on the runway for about 750 metres before skidding off the left edge of the runway. In their safety investigation report, investigators from the Singapore Transport Safety Investigation Bureau (TSIB) report that: It then flipped over and came to rest on the grass turf beside the runway. Shortly after, the tail section of the aircraft caught fire, which was extinguished by Changi Airport’s airport rescue and firefighting service. The pilot, who was the sole occupant of the aircraft, extricated himself and was not injured. No pre-existing defects were found with the aircraft. Nose Wheel Steering (NWS) System Background The TSIB investigators explain that: For the directional control of an aircraft on ground, a pilot would first use NWS, when the aircraft speed was low, and use the rudder at higher speed, as the rudder would be ineffective at low speed. The pilot would disengage the NWS and start using the rudder for directional control by pushing a switch on the control stick. Before the pilot did so, he had to manually align the nose wheel with the aircraft’s nose. If the nose wheel was not properly aligned…at the time of NWS disengagement, the nose wheel would be cocked in this unaligned condition. If rudder input was made after the disengagement of the NWS and if the NWS was re-engaged, the nose wheel would reset itself at the time of the NWS re-engagement to an angle corresponding to the last rudder pedal input. Analysis The aircraft started to veer towards the right edge of the runway as soon as the NWS was disengaged. This was because the nose wheel was not perfectly aligned with the aircraft’s nose, having been set at 1.31° to the right at the time of NWS disengagement. The ROKAF flying display team experienced a tail wind during the take-off. [However, the pilot had] no prior experience taking off with a tail wind in this aircraft type. As part of the formation take-off procedure, the pilot was maintaining visual reference to the lead aircraft of his group. Even though the actual aircraft speed was approximately 51.4 knots due to the tailwind, the pilot estimated the aircraft speed to be more than 60 knots at the point of disengaging the NWS, based on his previous take-off experience in head wind conditions. As such, there was insufficient aerodynamic forces to correct the direction of travel, when the pilot attempted to correct the veering of the aircraft to the right by applying full left rudder. The pilot managed to prevent the aircraft from veering further off the right edge of the runway by re-engaging the NWS. When he re-engaged the NWS, he was providing full left rudder input. This caused the aircraft to swing abruptly towards the left…after [the] NWS re-engaged. With the NWS remaining engaged, the pilot’s subsequent directional control inputs resulted in over-correction of the aircraft’s path of travel, which led eventually to the zigzag motion of the aircraft before it exited the left side of...
read moreLufthansa MD-11F Nose Wheel Detached after Maintenance Error
Nose Wheel Detached from Lufthansa Cargo MD-11F D-ALCM after Maintenance Error On 10 November 2016 Lufthansa Cargo McDonnell Douglas MD-11F D-ALCM suffered damage when the left-hand nose-wheel detached, bounced and repeatedly struck the underside of the fuselage on landing in Buenos Aires, Argentina on a flight from Curitiba, Brazil. The Junta de Investigación de Accidentes de Aviación Civil (JIAAC), the Argentinian safety investigation body, released their safety investigation report (in Spanish only) on 31 October 2018. The JIAAC report the wheel had been changed by Lufthansa personnel one day and 5 sectors previously in Dakar, Senegal after damage caused by FOD had been found. The investigators determined that a fixing pin on a separator (fitted between the wheel and the wheel nut), designed to stop the separator rotating, had not been installed. This omission allowed the wheel nut to back-off and detach, followed by the wheel. Unfortunately no other information is provided on the circumstances of the wheel change. The investigators raised one recommendation that Lufthansa “conduct a review of the procedures for quality control of the tasks of maintenance, particularly in remote bases”. Other Safety Resources Aerossurance has previously written on these associated topics: Airworthiness Matters: Next Generation Maintenance Human Factors Over the last 10-15 years, much attention has been focused on maintenance human factors training and reporting & investigating errors. While we could concentrate on simply doing more of these and certainly can find ways to do these things better, perhaps the next generation approach needs to include a much wider range of activities. Aircraft Maintenance: Going for Gold? Should we start treating maintenance personnel more like athletes who need to achieve peak performance every day? James Reason’s 12 Principles of Error Management B747 Landing Gear Failure Due to Omission of Rig Pin During Maintenance Maintenance Human Factors in Finnish F406 Landing Gear Collapse Safety investigators discuss the associated maintenance human factors and inadequacies in the type’s maintenance instructions. B1900D Emergency Landing: Maintenance Standards & Practices The TSB report posses many questions on the management and oversight of aircraft maintenance, competency and maintenance standards & practices after this serious incident. We look at opportunities for forward thinking MROs to improve their maintenance standards and practices. Singapore Airlines B777 41t Fuel Discrepancy Incident UPDATE 3 June 2020: Beechcraft 1900C Landing Gear Collapse at San Antonio, TX UPDATE 12 October 2020: Frozen Dash 8-100 Landing Gear After ‘Improper Maintenance Practices’ Say NTSB Also see our review of The Field Guide to Understanding Human Error by Sidney Dekker presented to the Royal Aeronautical Society (RAeS): The Field Guide to Understanding Human Error – A Review Aerossurance worked with the Flight Safety Foundation (FSF) to create a Maintenance Observation Program (MOP) requirement for their contractible BARSOHO offshore helicopter Safety Performance Requirements to help learning about routine maintenance and then to initiate safety improvements: Aerossurance has extensive air safety, operations, 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 moreFirefighting Helicopter Wire Strike
Firefighting Helicopter Wire Strike On 17 June 2017, Airbus Helicopters AS350B3+ F-HETH, operated by Sky Helicopteros, took off from Hoyos, in Céceres, Spain at approximately 20:30 to take part in fighting a fire in the town of Garrovilias de Alconétar, 30 miles away. The Spanish accident investigators from the CIAIAC say in their safety investigation report that: While flying to the fire…the pilot’s area of operations was changed several times, as a result of which he calculated that he would only have time to make two water drops… Once in the area of operations, he…flew to a nearby reservoir to pick up water. After making an initial drop without problems, he returned to the reservoir to pick up more water, but while doing so, the pilot suddenly saw power lines in front of him. He made an evasive maneuver [banking at 45°] in an unsuccessful effort to avoid striking the power lines. The impact took place at around 21 :29. After the wire strike, the pilot made an emergency landing to check the damage. The next day [18 June 2017], following a check by the company’s mechanic, the helicopter was flown from the accident site to the Serradilla helicopter base. which was the closest one, for a more thorough check. …after impacting the cable, the mechanic did a general visual inspection of both the blades and the rest of the helicopter. Specifically, he checked the blades from the ground, and then climbed on the helicopter to inspect them from the height of the leading edge. The mechanic was not looking for a small defect, but rather for a potential mark left by a cable cut by the blade. He therefore thought that the distance from which he did the visual check was adequate for this task. As a result, he did not inspect the blades from a short distance. He identified some damage, including a slight dent to the tip of one blade (yellow blade) which he considered minor. He did the tasks in the AMM for the cable cutter and the yellow blade and he issued a Return to Service Certificate. Later, on 20 June 2017, after having operated normally since the day of the accident, the company’s mechanic saw some marks on one blade (the blue blade) that seemed to have been caused by the impact with the lines. These impact marks had not been detected earlier. The maintenance mechanic concluded that the blade had to be replaced, and the helicopter was grounded. On 27 June 2017, the blue blade was replaced and the aircraft was returned to service, after which it operated normally. Observations On the first run the helicopter picked up water north east of the cables and they were behind and out of sight. On the second run the helicopter approach further south, where the cables were in an area in shadow as the sun was low. The pilot commented that: The lines were close to the ground. Normally power lines are higher up. He could not see the power line towers during the reconnaissance flight of the area due to the low light and to the large amount of smoke that was being dispersed by the swirling wind. He thought he would have been able to make out the power lines if it had been earlier in...
read moreFallacy of ‘Training Out’ Error: Japanese AS332L1 Dropped Load
Fallacy of ‘Training Out’ Error: Japanese AS332L1 Dropped HESLO Load On 23 September 2017 an Airbus Helicopters AS332L1, registered JA6717 and operated by Nakanihon Air Service, dropped the contents of an underslung bucket, a 2.7t load of stones, immediately after taking off from the Kojima temporary helipad in Kitagawa-village, Aki-gun, Kochi Prefecture. The helicopter was ferrying supplies to a construction site, operated single pilot with a crewman (‘onboard mechanic’). HESLO Incident Flight According to the Japan Transport Safety Board (JTSB) safety investigation report the crewman sought to communicate with a trainee ground crewman by radio concerning their load rigging: ….while holding a radio in one hand, and he reached to operate the transmit switch of the communication radio of the control box immediately after the Aircraft took off from the cargo sling point. At this time, he mistakenly operated the open/close switch for the bucket instead of the transmit switch, and as a result the bucket opened and the stones (approximately 2.7 tons) fell [approximately 80m from the helipad]. The aircraft retuned to the temporary helipad on what was the aircraft’s 59th helicopter external sling load operation (HSELO) flight of the day. There were no injuries or damage due to the inadvertent load drop. JTSB report that: ….the onboard mechanic [who had 23 years experience in the role] was not feeling fatigued. In addition, at the time that he attempted to operate the send switch, the onboard mechanic was thinking about how to warn the trainee and was not looking at his hand. The JTSB explain that: The control box used to operate the external sling system including opening and closing of the bucket and to operate the radio was installed on the forward left side of the cabin behind the cockpit seats. The onboard mechanic was in charge of operating it. A [radio] switch box was installed on the right side of the control box, and the bucket open/close switch was installed on the bottom of the switch box. The bucket open/close switch is a push button. The bucket opens during the time the button is pushed. The transmit switch of the communication radio is installed on the lower front side of the control box. Moving the switch down (to the “RAD” position shown below) puts the radio in the transmit mode. JTSB Analysis The JTSB say (our emphasis added): It is certain that the onboard mechanic had received the necessary education and training. Regarding the onboard mechanic operated the bucket’s open/close switch by mistake instead of the communication radio’s transmit switch, it is probable that this occurred when, while in a state in which his attention was focused on thinking about how to communicate a warning to the trainee and his attentiveness to the bucket’s operation was faded, the onboard mechanic unintentionally operated the bucket’s opening, which was an action that he had been conducting repeatedly until that time. Additionally, it is somewhat likely that the onboard mechanic did not notice the mistake in the switch he was about to operate because he was not looking at his hand when operating the switch. They go on to explain (again with our emphasis added): The bucket’s open/close switch had a design that opened the bucket simply by pressing the open/close switch and did not have a mechanism to prevent wrong operation. It is probable that using...
read moreLow Viz Helicopter CFIT Accident, Alaska
Low Viz Helicopter CFIT Accident, Alaska (TEMSCO Airbus AS350B2 N94TH, 6 May 2016) On 6 May 2016, Airbus Helicopters AS350B2 N94TH, operated by TEMSCO Helicopters, collided with snow-covered mountainous terrain about 4 miles southeast of Skagway, Alaska in a Controlled Flight Into Terrain (CFIT). The helicopter had departed from a remote landing site, surrounded by mountains, on the Denver Glacier on a visual flight rules (VFR) flight with internal cargo. Instrument meteorological conditions (IMC) were however reported on the Denver Glacier at the time. The non-instrument-rated pilot was fatally injured. The Accident Flight The US National Transportation Safety Board (NTSB) safety investigation report (released in October 2018) explains that: Alaska Icefield Expeditions contracted with TEMSCO to provide helicopter support for the movement of personnel, dogs, and cargo. The purpose of the flight was to transport dog camp company personnel (mushers) and dogs (Alaskan Huskies) from…Skagway to a remote dog camp on the Denver Glacier in the Tongass National Forest, about 5 miles southeast of Skagway. The pilot was ready to begin flight operations at 0800, but low ceilings prevented flight operations. The pilot attended company orientation training at 0900, and, at 1300, he provided helicopter loading training for new TEMSCO employees. At 1530, the pilot completed the training and evaluated the weather for flight operations. The pilot determined that the wind conditions were unsuitable at the time but were forecast to improve later in the afternoon. At around 16:45 the pilot commenced the first of 7 planned round trips. At 1840, the helicopter departed for the sixth trip with 1 musher and 12 dogs onboard. As the helicopter passed through Paradise Valley, the passenger reported that the valley itself was “wide open” with a rainbow present, but he and the pilot could see that the clouds were “moving in” as the helicopter approached the Denver Glacier. The passenger reported that the clouds were “thick,” and he could not see up the glacier toward the dog camp. The passenger further reported that the western mountain wall near the glacier was visible at the time, so the pilot elected to follow the wall into the dog camp “very slowly.” He stated that the helicopter was “very low” with regard to the bluff and was closer to the wall than he had ever been on previous flights up to the dog camp. The dog camp manager reported that just before the sixth flight arrived, the wind speed was up to 20 to 30 mph, and it was snowing. The clouds had moved in and covered the bluff; visibility was about a 1/4 mile looking toward Paradise Valley. The helicopter landed at the dog camp, and the musher and 12 dogs were unloaded. Before the pilot left, he signaled for the dog camp manager and told him that he was “not coming back in this weather.” The dog camp manager verbally agreed. The dog camp manager told the pilot to be safe, and the pilot said to the dog camp manager, “but don’t give up on me yet.” The NTSB suggest this last statement would be consistent with self-induced pressure to complete the flying programme. The FAA’s Helicopter Flying Handbook, FAA-H-8083-21, states: There are numerous classic behavioral traps that can ensnare the unwary pilot. Pilots, particularly those with considerable experience, try to complete a flight as planned, please passengers,...
read moreHelicopter Engine Unapproved Repair Leads to Forced Landing Damage
Helicopter Engine Unapproved Repair Leads to Forced Landing Damage On 3 June 2016, Bell 407 N4999, operated as an air ambulance by PHI‘s Air Medical division for Welmont Hospital, was damaged when it landed hard during in a forced landing into a parking lot near Mountain City, Tennessee. The impact spread the skids and resulted in substantial damage. The Rolls-Royce 250-C47B powered helicopter had suffered a partial loss of engine power during the initial climb after collecting a patient. The pilot suffered minor injuries and the two medical personnel and the patient were uninjured. NTSB Safety Investigation The US National Transportation Safety Board (NTSB) explain in their safety investigation report that: The pilot stated that during initial climb, about 125 feet above ground level, he heard a loud “bang” that was accompanied by a left yaw and rapidly increasing measured gas temperature (MGT). The pilot advised the crewmembers that he was rejecting the climb and landing immediately. The pilot further stated that he had to maneuver the helicopter right to avoid ground personnel, level the helicopter with cyclic control, and used all available collective to cushion the landing. Review of data downloaded from an engine monitor revealed that during the accident takeoff, the MGT increased beyond maximum for takeoff while the power turbine rpm decreased. Examination of the engine at the operator’s facility revealed a partial separation of the compressor diffusor, which allowed intake air to leak prior to combustion. Examination of the compressor diffuser [at the manufacturer’s lab] revealed that a portion of the aft plate had separated near a braze joint [in tensile overload]. The Rolls-Royce designed aft plate is a single, unbrazed component. Examination of maintenance records revealed that the compressor diffusor had been overhauled by overhaul shop Aero Propulsion previously. It was installed around 98 flying hours prior to the accident. According to the FAA principle maintenance inspector (PMI) of the repair facility, a machinist had joined a second ring to the compressor diffuser aft plate using a brazing process. Significantly: There was no approval (neither through the engine manufacturer nor the FAA) for that process… …it is possible that the machinist performed the procedure to correct a mistake he had made during a dimensional shim repair, which was approved through the FAA designated engineering representative (DER) program. According to the Quality and Engineering Manager at the repair facility, ultrasonic testing also failed to identify the unapproved repair. An immediate corrective action for the repair facility was to suspend dimensional shim repairs indefinitely. The repair facility also ensured that their three-tier approval process (engineering, quality and management) was required for any fixture, tooling, drawing, or process before it was performed and that all necessary personnel were trained in that method. The machinist no longer worked for the repair facility and had left the company prior to the accident. PHI have stopped accepting engines with repaired diffusers. NTSB Probable Cause An incorrect and unapproved repair of the engine compressor diffuser performed by a machinist at a repair facility, which resulted in failure of the compressor diffuser aft plate and a partial loss of engine power. Other Safety Resources Machining Defect Cause of V2500 Failure Micro FOD: Cessna 208B Grand Caravan Engine Failure & Forced Landing US HEMS EC135 Dual Engine Failure: 7 July 2018 Hard Landing after VRS on Approach to a Hospital Site USAF F-16C Crash: Engine Maintenance...
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