Taiwan Night Medevac Helicopter Take Off Accident
Taiwan Night Medevac Helicopter Take Off Accident (NASC UH-60M Black Hawk NA-706) On 5 February 2018 Sikorsky UH-60M Black Hawk helicopter NA-706 of the Taiwanese Ministry of the Interior National Airborne Service Corps (NASC), conducting a nighttime air ambulance medevac flight, departed Lanyu Airport on Orchid Island off the South East coast of Taiwan. Contact was lost with the helicopter approximately 81 seconds after take off as it crashed into the sea. The 6 persons on board (two flight crew, one rear crew, a medical passenger, the patient and a family member) were killed. History of the Accident Flight In their safety investigation report (issued on 24 September 2019 and only available in full in Chinese) the Taiwan Transportation Safety Board (TTSB), which recently replaced the Aviation Safety Council (ASC) of Taiwan, explain that the aircraft had displayed ‘FD COUPLE FAIL’ and ‘FLT DIR FAIL’ warning captions on the outbound flight to Lanyu. The crew did not discuss these and they extinguished before landing (at 23:38 LT). The crew did a briefing on the take off during a quick turnaround, departing at 23:48 LT. The environment featured ‘black-hole’ conditions. These conditions “typically occur over water or over dark, featureless terrain where the only visual stimuli are lights located on and/or near the airport or landing zone”. They are conducive to spatial disorientation. The ‘FD COUPLE FAIL’ and ‘FLT DIR FAIL’ warnings briefly reappeared about 19 seconds into the flight and again were not discussed before they extinguished again after 3 seconds. It appears (based on our translation from Chinese) that an airspeed hold autopilot mode was engaged. The aircraft was now climbing at around 95 knots. The helicopter encountered an increasing tailwind about 23 seconds after taking off, that reached 40 knots. The crew mention windshear and turbulence. It appears the autopilot dropped out in the turbulence but the Pilot Monitoring commented “Now is a positive rate of climb, it doesn’t matter”. However, the TTSB state that while the aircraft was now at 197 ft and 106 knots 44 seconds after take off, the rate of climb had dropped to 192 ft/min. Furthermore the nose starts to pitch up (peaking at 22.2º), speed decreases and climb rate slows and then the aircraft starts to descend. At 78 seconds after take off the aircraft is at 133 ft but the rate of descent is now 2.100 ft/min. Moments after the CVR/FDR stop recording. The aircraft impacted water that was 1000m deep. The aircraft was not equipped with an Emergency Flotation System (EFS). TTSB Analysis The TTSB note that the NASC “do not provide the complete Standard Operating Procedures (SOPs)” nor did the flight crew totally follow the SOPs that were in place. Additionally: The NASC failed to plan the appropriate training of the flight crews. [Specifically they] did not properly arrange the training resources of the UH-60M aircraft, and did not plan the suitable ground course for the advanced models. [T]raining hours of the simulators were insufficient [too]. The NASC does not define the minimum requirements related to night flight and instrument flight time, has no specific complete training material for Crew Resource Management [CRM] training and and did not define the weather standards for night EMS… TTSB Conclusions The TTSB conclude that: The flight crew’s threat management, situation awareness, communication and decision-making capabilities as well as the understanding of the aircraft system were not sufficient. They did not choose the appropriate takeoff mode at takeoff under the night circumstance and unsteady wind condition. During...
read more‘Crazy’ KC-10 Boom Loss: Informal Maintenance Shift Handovers and Skipped Tasks
‘Crazy’ KC-10 Boom Loss: Informal Maintenance Shift Handovers and Skipped Tasks On 1 November 2016 US Air Force (USAF) Boeing KC-10A Extender tanker 83-0080 of the 60th Air Mobility Wing departed Travis Air Force Base (AFB), California for a training exercise. As the crew prepared for aerial refuelling (AR) the Boom Operator lowered the Aerial Refuelling Boom. The KC-10’s Boom Operator sits at the rear of the aircraft with a panoramic view and controls refuelling through a hand controller and a digital fly-by wire system. The USAF Accident Investigation Board (AIB) reported that this was only the second time this boom had been lowered in-flight since major maintenance on 13 October 2016, just over 2 weeks earlier. On the first occasion (30 October 2016) the boom drifted to aircraft left approximately 10º-15º. Based off of post-mishap analysis by the AIB, it was determined that the Boom Control Assembly (BCA) had a voltage bias in the roll axis to the aircraft’s left and the gimbal yoke assembly was out of design specification tolerances. After the aircraft returned, the crew informed maintenance of the boom’s actions. Despite half of the rotary crank missing, the rotary drive shaft remained static and engaged with the crank while the boom was stowed. Consequently, the maintenance personnel, did not detect the anomaly and released the aircraft for flight. During the incident flight two days later on 1 November 2016: Immediately after lowering the boom, it began to move erratically, oscillating to the aircraft’s right and left in a U-shaped pattern, well outside of its structural limits. After oscillating for approximately two minutes, the boom hoist cable broke. The Boom Operator described the boom as having gone ‘crazy’. Approximately two minutes later, the gimbal separated from the A-frame gimbal mounts, but remained connected to the fuselage by hydraulic and electrical lines. [Ultimately] the boom completely separated from the aircraft and fell in an open field in Idaho. [The crew safely] landed the aircraft at Mountain Home AFB, Idaho without incident. The total monetary value of government loss was $6,529,845.71. The AIB president identified two causes: The first cause of this mishap was a sheared Dual Rotary Voltage Transducer (DRVT) rotary crank that resulted from DRVT rotary bearing misalignment. This was due to the earlier 10º-15º drift making the DVRT rotary crank contact the internal mechanical stop and causing it to shear. This provided the aircraft’s boom control unit (BCU) with continuous, inaccurate roll position indications. As a result, the BCU compensated with lateral movement commands in both directions, driving the boom beyond its operational and structural limits. The second cause, related to the first, was the [Boom Operator’s] failure to turn off the boom flight control switch in a timely manner. Turning off this switch would have disabled the BCU. This would have neutralized the boom flight control surfaces, and prevented the boom from departing the aircraft. They also decided that “substantially contributing” was: …the failure of maintenance personnel to comply with technical orders prevented the possible detection of an erratically performing DRVT… In particular: The 60th Maintenance Squadron (MXS) Hydraulics Section depended on informal hydraulics turnover logs and word of mouth instead of recording the completed task steps [as required by USAF procedures]. Additionally, the time required to remove and replace the gimbal assembly and to remove and reinstall the boom spanned over four shifts. The failure to...
read moreEC135P2+ Loss of NR Control During N2 Adjustment Flight
NPAS EC135P2+ G-POLA Loss of NR Control During N2 Adjustment Flight National Police Air Service (NPAS) Airbus Helicopters EC135P2+ G-POLA suffered a serious incident on 5 April 2018 over Northumberland, UK when an engine power turbine speed (N2) adjustment resulted in a loss of main rotor speed (NR) control. The UK Air Accidents Investigation Branch (AAIB) report that: In November 2017, after an engine change, a deferred defect log (DDL) entry restricted the helicopter to 4,500 ft density altitude (DA). To remove this restriction the helicopter required an N2 adjustment flight at 9,500 ft DA. AAIB explain that the Pratt and Whitney Canada (PWC) PW206B2 powered EC135P2 has a ‘cross-talk’ capability between the two engine Full Authority Digital Engine Control (FADEC) units and so it is possible for one adjuster to set N2 in both engines simultaneously. When a replacement engine is fitted, the cross-talk facility automatically matches both engines. Normally the remaining, and already correctly set, engine would cross-talk to the replacement engine and N2 would be correct. However, AAIB say “occasionally adjustments are required”. The N2 adjuster is a small rotary switch set into the overhead panel… To operate the adjuster, a small flat-bladed screwdriver must be inserted which then enables it to be turned clockwise or anticlockwise. The pilot planned to use the opportunity of good weather at his base of Newcastle Airport to perform the adjustment flight. He and a maintenance engineer, who was to accompany him, together reviewed Section 76-10-00, 5-5 – ‘Setting N2 Speed’ and Section 05-60-00, 6-4 ‘Ground Check Run and Functional Check Flight…’ of the the Aircraft Maintenance Manual (AMM). According to the AAIB they “did not specifically brief the possible hazards of performing” the flight. The pilot initiated a climb in accordance with the AMM procedure and called out the heights and temperatures for the engineer to record. They determined a pitch stop torque value at 9,500 ft DA of 67%, with an associated N2 of 103.2%. This was slightly lower than the required 103.8% N2 . The pilot asked the engineer to make an adjustment on the N2 adjuster, which he did. Initially there was no increase. However, after further adjustment, the N2 slowly increased at a constant rate. As the N2 reached 103.8% the pilot advised the engineer to stop the adjustment, and he did so. However, the N2 continued to increase through 104% and the NR began to increase at the same time. The pilot arrested the rising NR at 106% (the maximum continuous power‑on NR allowable) by raising the collective lever to full travel with a torque of 69%. At this point the NR overspeed warning light illuminated and the associated aural alert sounded. To contain the now increasing airspeed and resulting airframe vibration, the pilot adjusted the helicopter attitude and initiated a moderate climb. The pilot asked the engineer to reverse the adjustment as soon as possible, which he did, but with no effect. The pilot began to revert to manual throttle but had difficulty lifting the associated catches until he removed one of his flying gloves. The pilot commented that he: …wore thick gloves because he had calculated the OAT during the flight test would drop to around -15°C. However, these impeded his ability to lift the manual throttle catches, which he reflected could have been problematic had it happened close to...
read moreSAR Questions Feature in PNG AIC B427 Accident Investigation
Search and Rescue (SAR) Questions Feature in PNG AIC B427 PS-HSG Accident Investigation The Papua New Guinea (PNG) Accident Investigation Commission (AIC) has issued a preliminary report into an accident involving Bell 427 P2-HSG operated by Ballina Limited t/a Niugini Helicopters on 11 August 2019. UPDATE 5 January 2021: They have now issued their final report (updates have been added below). History of the Accident Flight The helicopter was conducting a Visual Flight Rules (VFR) ferry flight from Kokopo, East New Britain Province to Kimbe, West New Britain Province, when it impacted the water, over a reef 3.1 nm NW of Baluma township. The pilot, the sole person on board, suffered minor injures and was rescued after c 45 minutes with the assistance of local boat owners who had witnessed the accident. Investigators say that: After completing a passenger flight from Kimbe to Kokopo, the pilot of the helicopter departed back to Kimbe at 10:02. About 30 nm from Kimbe, the pilot made a radio broadcast [on VHF] reporting that he had commenced his descent from 8,000 ft into Kimbe. The helicopter was estimated to arrive in Kimbe at 11:09. The pilot (a 51-year-old New Zealander with 6549 total fly hours, 346 on type) told investigators that he descended to about 3000 ft and commenced an autorotation exercise “to check the autorotation RPM which had been adjusted by the engineers during an unscheduled maintenance activity the day before”. The pilot did not consider the position and distance from land when he planned and conducted the autorotation exercise. This was evident because he commenced the autorotation along his normal flight track when the aircraft reached nominated entry altitude 3,000 ft. In accordance with the FAA Advisory Circular(AC) No: 61-140A on Autorotation Training, most recorded autorotation exercise related accidents have been attributed to their recovery phase (transition back to powered flight), at the position, at 1,000 ft, where the pilot attempted his recovery, there was no land close enough for the pilot to land the helicopter in any emergency descent. See our past article: Inappropriate Autorotation Training. The AIC report that: The pilot reported that everything seemed normal until he commenced action to transition back to powered flight (recover), from simulation at around 1,000 ft, where he received the low rotor RPM warning. He then momentarily glanced at the torque gauge, and recalls sighting an abnormal reading which prompted him to think that one of the helicopter’s engine had failed. The pilot stated that he immediately lowered the collective and rolled the throttles to idle allowing the helicopter to enter an emergency autorotation descent straight ahead along its planned track. He immediately activated the company’s third-party tracking system (Spidertracks) ‘SOS’ at about 11:04 LT just before descending through 1000 ft, and broadcast a ‘Mayday’ on the HF radio during the emergency descent, but could not recall the altitude at which he made the call. He added that he did not make another call or pursue a response from Air Traffic Services (ATS) because he was more focused on handling the emergency event. The alleged Mayday call made by the pilot on HF was not received by ATS. The HF transmissions were convoluted with static interference. The pilot further stated that at some stage, as he was getting closer to the water, he realised that the engine power was...
read moreEC135P2 Spatial Disorientation Accident
EC135P2 N62UP Spatial Disorientation Accident On 25 May 2017 an Airbus Helicopters EC135P2, N62UP, was destroyed and the pilot, the sole person on board, was killed in a high energy impact near New Castle, Delaware. The helicopter was an air ambulance owned by the University of Pennsylvania and operated by Metro Aviation for the PennStar HEMS service. History of the Flight The flight, operated as a a Part 91 “personal flight”, originated from Atlantic City International Airport (ACY), New Jersey, 36 minutes earlier so the pilot could practice instrument approaches at New Castle Airport (ILG), Wilmington, Delaware in Instrument Meteorological Conditions (IMC). The US National Transportation Safety Board (NTSB) state in their safety investigation report (released 10 October 2019) that about 30 mins before departure… …the pilot submitted a flight request form to the company, which documented the weather products he reviewed before the flight and indicated that he was aware of the reported and forecast weather conditions for the route before departure. After reviewing the request, weather, and risk assessment, the company’s operation control center approved and released the helicopter for the flight five minutes after the request was submitted. The terminal area forecast published earlier that morning and valid for the pilot’s anticipated time of arrival at the destination indicated that the visibility would be 6 statute miles with an overcast ceiling at 1,200 ft agl; though the most recent surface observation report contradicted the forecast, indicating that the visibility was 4 statute miles in rain and the overcast ceiling was at 500 ft. During the flight Air Traffic Control (ATC) provided radar vectors to the pilot for an instrument landing system (ILS) approach. The helicopter intercepted the localizer course about 1 nautical mile (nm) outside the approach gate. The controller then cleared the pilot for the approach with a restriction to maintain an altitude at or above 2,000 ft mean sea level (msl), which was both the assigned altitude and the intermediate altitude for the approach, until established on the approach and to contact the control tower at the destination airport. The pilot acknowledged the clearance and contacted the tower controller shortly thereafter. After checking in with the tower controller; the helicopter maintained 2,000 ft msl as it continued through the glideslope and crossed over the locator outer marker, which had a published crossing altitude of 1,842 ft msl. As the helicopter reached a point about 3 nm inside the outer marker, while flying at an altitude about 2,000 ft msl, the pilot declared a missed approach, telling the controller that he had received “some bad vectors at the very end” and that he wanted to “just line up and come back around again.” The controller advised the pilot to fly the published missed approach procedure (a straight-ahead climb to 900 ft msl and then a left climbing turn toward the next navigational fix, at an altitude 2,000 ft msl). The helicopter then climbed straight ahead to an altitude of 2,525 ft msl in 9 seconds, before it turned right and started descending rapidly. NTSB comment that: The helicopter’s calculated rate of climb before it began to descend was about 3,000 ft/min, while it’s calculated groundspeed was about 120 knots. This climb rate and speed were not consistent with the pilot using the helicopter’s automatic flight control system go-around mode because they were well above the...
read moreATR72 Missed Damage: Maintenance Lessons
ATR72 VH-FVR Missed Damage: Maintenance Lessons (Virgin Australia Regional Airlines [VARA] VH-FVR) In 2014 we first reported on the preliminary information from the Australian Transport Safety Bureau (ATSB) on a serious incident with a Virgin Australia Regional Airlines (VARA, formerly Perth, WA based SkyWest) ATR 72 VH-FVR on 20 February 2014. We followed up on this with a more detailed report on the day the ATSB issued a first Interim Report in June 2016 which we updated further after the second Interim Report in May 2017 in and the Final Report in May 2019 (a report issued 63 months after the serious incident!). This article looks specifically at the maintenance failures that followed the damage. History of the Flight While operating a scheduled passenger flight from Canberra to Sydney, the ATSB say that: While passing through about 8,500 ft, the aircraft encountered a significant windshear that resulted in a rapidly decreasing tailwind. This led to a rapid increase in airspeed, with the airspeed trend vector (displaying predicted speed on the primary flight display) likely indicating well above the maximum operating speed (VMO) of the aircraft of 250 kt. The first officer reduced engine power and made nose-up control inputs in an attempt to slow the aircraft. The Aircraft Commander (the Pilot Monitoring) “perceived a need to take over control of the aircraft, with the intention of preventing the airspeed exceeding VMO” but only announced 5-6 s later that he was taking control. In the interim the flight crew had made opposing inputs and thee aircraft sustained a pitch disconnect in which aerodynamic loads “exceeded the strength of the horizontal stabiliser and resulted in significant damage.” Crucially the damaged went undetected during a subsequent inspection and was only detected 13 flights later. Continuing Airworthiness, Maintenance, Quality System and Fatigue Risk Background Maintenance of the VARA ATR72 was contracted to Brisbane based Toll Aviation Engineering (TAE), an arrangement commenced by SkyWest in 2011. Operating within the VARA CAMO [Continuing Airworthiness Management Organisation approved by CASA in accordance with CASR Part 42 8 months earlier] were maintenance watch personnel who were tasked to coordinate the rectification or deferral of defects, provide technical support to line maintenance personnel, and brief management as required. In consultation with the CAMO manager or fleet manager, the maintenance watch engineer was to decide on the appropriate action to ensure any disrupted aircraft were safely returned to service. Part of the coordination role was liaison with each [line station] to ensure adequate resources were available to perform the assigned work. If additional personnel, equipment or hangar space was required…they applied to the TAE production and planning section in Brisbane which could provide purchase orders during their normal working hours of that section. However, ATSB note that: …it would seem to be impractical for the maintenance watch engineer to proactively provide technical support and monitor resourcing at the Sydney line station. From a European perspective it is slightly odd that the VARA CAMO was expected to provide greater operational support and oversight than would be normal in Europe for a 3rd party maintenance organisation’s line station. For any significant line maintenance events, the Aircraft Line Maintenance Event Consideration Worksheet was to be used. This form was intended as a management and coordination guide for capturing essential data and provided notification protocols to ensure that a standard approach to control and coordination was applied to aircraft recovery. Furthermore: In 2012, the LAMEs involved in...
read moreGlider Controls Fail After Non Compliant Maintenance Embodying an AD
Glider Controls Fail After Non Compliant Maintenance Embodying an AD A single seat Rolladen-Schneider LS 4-b glider, registration PH-974, was making a local flight from Larserveld on 23 April 2018. According to the Dutch Safety Board (DSB) in their investigation report: During the winch launch…the air brakes opened unexpectedly. The air brake control rod had slipped out of the locked position which was corrected by the pilot. After approximately one hour in the air and flying through mild turbulence, the problem of unlocking air brakes and corrective actions by the pilot recurred several times. At an altitude of approximately 1,100 metres the air brake control rod in the cockpit of the glider detached. From that moment on the pilot had little to no control of the air brakes and he decided to return to the airfield. The pilot used his right hand to hold the remaining part of the control rod and used his left hand to steer the aircraft. The landing was without any further problems. Safety Investigation After the flight, it was found that the air brake control rod had become detached from the rest of the mechanism. In 2017 several events had already taken place with this type of glider where a junction in the air brake control rod was about to fail. To address this potential unsafe condition, the aircraft manufacturer determined that a swivel needs to be installed similar to that used in…the…LS 4-a. A Technical Note (TN) 4048 was published on 30 November 2017 by the aircraft manufacturer, providing inspection and modification instructions. The European Aviation Safety Agency (EASA) assessed the problems…as a safety risk and made the technical note mandatory by issuing Airworthiness Directive AD 2018-0032 with an effective date 1 March 2018. This glider had been modified on 7 April 2018 to comply with that AD by a technician in the flying club’s workshop. During their investigation the DSB… …concluded that the wrong type of Loctite (243 [known as Blue Threadlocker, “a general purpose threadlocker of medium bond strength” instead of 638 [a “high strength retaining compound…for the bonding of cylindrical fitting parts”]) was used and the Loctite had expired 2 years ago. Furthermore, the weld in the control rod was not removed by a 13.5 mm drill as required by the TN, but with another drill. As a result the control rod was limited in its movement, which caused a bending moment on the air brake control rod junction. The weld also put pressure on the threading of the bolt in the swivel. As there was insufficient thread locking on the bolt, combined with the repeated rotational movement of the airbrake handle (needed to operate the airbrakes) the pressure on the threading resulted in loosening of the bolt. This resulted in a complete detachment of the swivel and so the air brakes could no longer be retracted fully. In a useful proactive initiative, the DSB surveyed technicians who had performed this modification in the Netherlands: The mechanics are of the opinion that in general the modification was not difficult to execute. Some mechanics however found the modification instructions not clear and reported that they had requested the aircraft manufacturer for help. Technical support provided by the manufacturer was considered adequate. For future modifications, KNVvL suggested the aircraft manufacturer provide a complete material listing…including not only the retrofit...
read moreMi-26T Arctic VRS Accident 28 November 2018
Mi-26T Arctic VRS Accident 28 November 2018 UTair Mi-26T helicopter RA-06029 crashed on 28 November 2018 with the loss of one life, the aircraft commander. Five other crew members survived, one with head and spinal injuries. The helicopter was returning from delivering 17 t of “building materials” to Naulskaya in the Nenets Autonomous Area. the 56 t Mi-26T can carry a maximum payload of 20 t. It is powered by two 11,400 shp D-136 turboshafts and has a 32 m (105 ft) main rotor diameter. Safety Investigation The IAC/MAK safety investigation report (only available in Russian) revealed that during a night VFR flight, the aircraft descended from 2000 ft to around 15o ft AGL, and slowed to c 30 knots, c 3 nm from its destination at Pizhma as the weather unexpectedly deteriorated. The crew had not received a more recent forecast while unloading at Naulskaya. The investigators say the helicopter impacted the ground 760m from Pizhma during a second approach attempt after entering a Vortex Ring State (VRS) while distracted by the visual search for the landing site. The accident was the result of the crew not making a timely decision to leave for the alternate aerodrome when the weather conditions on the landing site worsened to values lower than those set for VFR. The investigators say contributory factors included: unsatisfactory interaction of the crew approach at altitudes and flight speeds less than those established by the Flight Manual deficiencies in the selection of crew members capable of working away from base lack of an effective control of deployed crews deficiencies in the Safety Management System (SMS) which did not identify and reduce risk when performing operations in the difficult conditions of the Arctic. UPDATE 25 April 2020: Another dramatic Mi-26 accident is caught on video. Safety Resources AAIB Report on 2013 Sumburgh Helicopter Accident Hard Landing after VRS on Approach to a Hospital Site UPDATE 19 April 2020: SAR Helicopter Loss of Control at Night: ATSB Report UPDATE 18 July 2020: Vortex Ring State: Virginia State Police Bell 407 Fatal Accident UPDATE 3 October 2021: French Cougar Crashed After Entering VRS When Coming into Hover Mi-26 video 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 moreFatal Snowy Powerline Inspection Flight
Fatal Snowy Power Line Inspection Flight (H369HM, N4QX) A Hughes (later MD) 369HM N4QX, operated by Vista One Inc, impacted terrain near Perrysburg, Ohio on 15 January 2018, 72 minutes into a power line aerial observation flight. Both occupants, pilot and observer, were fatally injured. Police photographs at the accident scene further showed falling snow and flat light / white out conditions. Local TV news report (VIDEO). The Operational Tasking US National Transportation Safety Board (NTSB) say in their safety investigation report that Vista One holds a Part 133 Rotorcraft External Load certificate and conducts power line inspections under Part 91. The accident flight was the first leg of inspections of the Toledo Edison power grid from Bowling Green, Ohio to the Indiana/Ohio border over the following 4 weeks. Vista One’s power line inspection flights involved the helicopter flying along the line, circling each tower then continuing along the line. Vista One’s owner explained that: It was the responsibility of the crew member [the inspector sat in the rear on the right hand side], using binoculars and a camera, to inspect the towers and lines for the security of cotter keys, nuts, bolts, and so on. The pilot would position the helicopter skids above the static line, about 20 ft, during these flights. …it was typical for the helicopter to cover between 2 and 3 miles in an hour. In the accident report form, the owner stated that it was not normal to inspect the lines in snow and blowing snow due to the poor visibility and wind gusts. Toledo Edison is part of FirstEnergy, a company with a c$25 billion market capitalisation and annual revenues of c$11 billion. Safety Investigation Vista One told the NTSB that the pilot had departed from the company base at the Wayne County Airport, Wooster, Ohio, earlier that morning to pick up a power line inspector at Wood County Airport, Bowling Green, Ohio. The inspector had driven from his home in West Virginia. The pilot refuelled the helicopter during their 63 minute stop there. Security video showed the helicopter on the ramp in falling snow throughout this period. Witnesses described the snowfall as “moderate” at the time of departure. No explanation of why the flight was conducted in such conditions was forthcoming from Vista One or discussion by the NTSB of their operational control or flight following. The National Weather Service (NWS) forecast sub-zero air temperatures, east-southeast wind of 5 to 10 knots, overcast sky cover and light snow. In their safety investigation report the NTSB report the low-time pilot had logged just over 1,200 hours in helicopters, around 200 hours in the MD369. The pilot had logged less than 100 hours of simulated instrument flight time and no flight time in actual instrument conditions. The last simulated instrument flight (0.4 hours dual received) was conducted in September 2015 in a Robinson R44. The pilot had started work for Vista One in September 2017, so significantly this was his first winter with them, and had flown just over 300 hours for the company. Of note is that… …the company did not provide any training records for the pilot. The owner recalled conducting a training flight with the pilot the week before the accident but did not provide any specifics for that flight. The owner mentioned that the pilot had difficulty recalling how to clear the GPS track…. He also stated that the...
read moreB747-400F Tyre Explosion During Inflation
B747-400F Tire Explosion During Inflation The Singapore Transport Safety Investigation Bureau (TSIB) have reported on a tyre explosion on China Airlines Boeing 747-400F freighter B-18719 on 18 October 2018 during a turnaround at Singapore Changi. The aircraft had landed at 0443LT and was scheduled to depart two hours later. During a walk-around inspection, the tyre pressure of the No.11 tyre was found to be low. While the tyre was being inflated with nitrogen, the tyre burst. A tyre pressure gauge that a Technician had placed on the top of the tyre was propelled into the wing body fairing. The technician “felt a blast of cold air to the right side of his face” but was uninjured. The Safety Investigation The Aircraft Maintenance Manual (AMM) contains procedures for both Hot and Cold Tyre Pressure Checks. The cold check is Boeing’s preferred method and the hot check is intended for occasional use only. A cold check can be performed if the tyre has cooled for 2 hours or more. However the cooling time can vary depending on the weather conditions, ambient temperature etc. Boeing considers it acceptable to determine if the tyre has cooled to ambient temperature by touch. TSIB note that this “has an element of subjectivity”. The Licensed Aircraft Engineer (LAE) checked the tyre and believed it had cooled, noting it was raining heavily at the time. After assessing by touch that the tyre was not hot, he tasked Technician A to measure the tyre pressure while he himself went to the cockpit and noted that the brake temperature was indicated as “0” on a scale of 0 to 9 on the wheel synoptic page of the aircraft’s Engine Indicating and Crew Alerting System (EICAS). However, this was not conclusive as: “0” and “9” represented the Cold and Hot ends respectively. “0” corresponded to a brake temperature lying within the range from ambient temperature to 176ºC. Technician A used a manual tyre pressure gauge and determined the tyre pressure was 170 psi. The air operator had set a tyre service pressure of 200 (+5/-0) psi irrespective of the aircraft’s gross weight (which was within the range allowed by the AMM), so there had been a drop of 15% in pressure and so the tyre should have been replaced. It appears the LAE however erroneously calculated the drop from the minimum inflation pressure (185 psi) i.e 8.1%. That percentage allowed the tyre to be re-inflated subject to a tyre pressure checked again 24 hours. The LAE then instructed Technician A, who would be assisted by Technician B, to service No.11 tyre to 200 psi. During the inflation the tyre burst as described above. The examination of the burst tyre by the tyre manufacturer [Bridgestone] suggested that there was a pre-existing ply cord deterioration condition on the tyre and that this condition was consistent with the tyre having been operated under significantly low pressure prior to the incident. Indeed, had the tyre been appropriately serviced, it seemed very unlikely that the tyre pressure could have dropped to 170 psi. The ply cord deterioration was likely accompanied by a slow deflation of the tyre which was somehow not noticed during daily checks of tyre pressure or transit walk-around inspections. The integrity of the tyre was compromised progressively by the ply cord deterioration and it was during this incident that the tyre wall could no longer withstand the internal inflation pressure and...
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