Tight Cable Tie Nose Gear Jam
Tight Cable Tie Nose Gear Jam (Flybe Dash 8 Q400 G-JEDU) Flybe DHC Dash 8 Q400 G-JEDU made an emergency landing at Belfast International Airport with its Nose Landing Gear (NLG) retracted on 10 November 2017 after cockpit indications showed that the nose landing gear doors had not closed after landing gear retraction. There was an emergency evacuation and two of the 53 passengers sustained minor injuries. Evacuation was complicated as the forward left airstair door was at a shallow angle while the the rear door sill height was large. Safety Investigation In their safety investigation report the UK Air Accidents Investigation Branch (AAIB) state they… …determined that…the forward NLG doors starting to close while the NLG was still in transit to the up position. The NLG tyres contacted the forward doors, causing the NLG to rotate off-centre. Although the NLG subsequently retracted, the forward doors remained open and the tyres became jammed in the NLG bay. This prevented the nose landing gear from extending when subsequently commanded. [After the incident it was found that] the NLG alternate release cable remained jammed despite attempts to pull it using substantial force, however the uplock could be heard releasing when the cable was pulled. A crowbar was used to rotate and centre the NLG, releasing the right tyre from the jammed position; once the gear was centred, it extended under gravity and locked down. During a go-around at Birmingham International Airport on 1 November 2017, G-JEDU’s landing gear failed to retract when selected. A circuit was flown gear down and a safe landing made. Damage was found to the lower edge of the forward right NLG door and the door seal. The problem could not be replicated during subsequent maintenance. The forward right NLG door and door actuator were replaced and the aircraft returned to service. The AAIB reviewed Flight Data Monitoring (FDM) data and discovered that: …G-JEDU experienced slower than normal NLG retractions (12 seconds) during two sectors on 9 November 2017 and on one sector on 7 November 2017 (20 seconds). Additionally, slower than normal NLG retractions (12 seconds) were noted for the flight on 1 November 2017 where the landing gear failed to retract, and on the previous sector the same day… During a carefully controlled trial after the Belfast occurrence, anomalous inductance values were detected in a NLG up-lock sensor harness (‘NGLK 1’) when jams were reproduced. During removal of the harness it was noticed that there was little slack and a tight bend where it entered the bulhead connector. A computed tomography (CT) scan “identified that one of the two conductors in the NGLK1 harness was fractured…approximately 15 cm above the sensor. In addition, a number of sites which indicated the initiation of possible similar damage were identified”. The AAIB found that: The damage to the harness resulted from a cyclically-driven fatigue failure mechanism, which occurred because the harness had been secured with a non-flexible cable tie which restricted it from flexing during normal nose landing gear operation. However: The aircraft and landing gear manufacturers are aware of other instances of NGLK sensor harness failures in normal operation. During normal retraction, extension and steering operations, the NGLK harnesses are subject to dynamic movement and bending which can result in degradation and breakage of the internal wires. The landing gear manufacturer [had already] initiated a product improvement review...
read more“Shoulda gone around”: B727 Landing with NLG Retracted
“Shoulda gone around”: Kalitta Cargo B727 N720CK Landing with NLG Retracted On 28 January 2019, Kalitta Charters II cargo Boeing 727-2B6 N720CK, landed with its nose gear retracted at Tuscaloosa Regional Airport (TCL), Alabama. The operator is a Part 121 cargo airline based in Ypsilanti, Michigan that conducts just-in-time cargo operations for the automotive industry. They operated a fleet of 5 B727 aircraft and 9 other aircraft. According to the NTSB’s report: …about 12 miles from the airport the captain called for flaps 15 and gear down. After the gear was selected down, the CVR recorded the first officer stating, “yeah it’s down, but [unintelligble] the lights [unintelligble]” The crew reported that they noted a red warning light for the nose gear position, and heard the audible gear warning horn. The CVR recorded the captain queried, “what horn was that?” and the first officer (FO) responded, “[unintelligible] gear warning horn.” Surprisingly: The flight engineer (FE) stated that he recommended that they recycle the gear, the captain declined. The FO stated that he recommended that they go around to troubleshoot, the captain declined. The CVR recorded multiple automated “sink rate, pull up” warnings and the captain responded, “yeah, yeah, I got it.” The FO then queried, “you gonna go around?”, and the captain responded, “ah I’m gonna go… I got, it, I got it.” The captain reportedly stated that the airplane had a history of a microswitch issue, and pressed on the gear handle and light. As the power was reduced to idle, the gear warning horn and the GPWS audible alerts sounded. Curiously: The captain stated in an interview that he asked for the gear to be recycled, and also that he smelled smoke and did not want to delay. Neither the FO, FE, or non-revenue mechanic, reported these items, nor were any of these items audible on the CVR. What is clear however is that: The captain continued the approach and after landing, upon derotation, the forward fuselage contacted the runway and the airplane quickly slid to a stop with the nose gear retracted. After the airplane came to a stop, the captain stated, “it wasn’t down,” and the FO made a radio call to tower. About five seconds later the FO stated, “shoulda gone around,” and the captain responded, “yeah, shoulda.” The crew did not declare an emergency or call for fire / rescue. The NTSB also report that: One day prior to the accident, a different flight crew experienced an indication that the nose landing gear failed to extend. This flight was also landing at TCL, and the crew reported they were high and fast, and that power was near idle, and flaps were in transit when the gear was selected down. After extending the landing gear, the crew received a red warning light for the nose gear. The green nose gear down and lock light was not illuminated. The crew requested delaying vectors and referenced the abnormal checklist for landing gear indications. They attempted to swap out the green down and lock bulb with another bulb but still did not receive the light. The gear was cycled, the red unsafe indication extinguished, and they then received a green down and lock indication for the nose wheel. Significantly: The event was not written up in the maintenance logbook. The Captain [of the previous flight]...
read moreTaiwan 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...
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