Software Bug and High Winds Down Drone
Software Bug and High Winds Down Drone The UK Air Accidents Investigation Branch (AAIB) has reported on an accident involving a 2.4kg Aeryon Skyranger R60 Unmanned Air System (UAS) / quadcopter drone serial number SR9112798 on at 03:30 Local Time on 18 January 2018 at Brixton, London. The Accident Flight The AAIB report that: The UA [Unmanned Aircraft] was being operated in a built-up area at night, with appropriate authorization from the CAA. It was carrying a camera and was being operated by a pilot and observer. Both the pilot and observer had received training on the Skyranger R60 and been issued with the appropriate permission by a CAA National Qualified Entity. They were however relatively inexperienced at operating UAS at the time of the accident. Prior to the flight, an inspection of the area was carried out to identify suitable takeoff and landing sites and to check for any local hazards. A check of the UAS was also completed with no faults identified. Flight settings were loaded into the ground control unit, with a programmed maximum operating height of 121 m. The pilot stated he then lifted the UA into a 1.5m hover to complete calibration and safety checks, which all proved satisfactory. The UA was then climbed towards its planned operational height, but as it reached a height of about 50m it started to drift and the ground control unit displayed a ‘Strong Winds [N10]’ message . The UA, unable to hold position, then drifted out of sight over an adjacent five-storey building, generating a ‘Position Control Warning’. Aware the UA was not following the intended flight track the pilot moved to regain sight of the UA without success. The ground control unit then indicated a loss of control signal. The UA camera image was lost and the control screen switched to the home screen, with no apparent connection indicated with the UA. The UA did not return to the pre-programmed home position (the takeoff point) and a search of the local area revealed the UA had impacted the ground about 30 m from the take-off site, breaking into several pieces. The Safety Investigation The UA’s internal data storage card was damaged on impact, preventing data recovery. Flight logs recorded on the ground control unit and video imagery was however recovered. These indicated that after the control link was lost, the UA went through a number of direction and height changes before descending and impacting a tree top at a height of approximately 15 m, then falling to the ground. The system was loaded with that the manufacturer had become aware on 23 December 2016 contained an error that would become evident when “a ‘non-fatal’ message was generated and the UA became unable to hold position”. In this occurrence the drone had automatically entered the ‘return home’ mode when the high winds prevented it holding station. This error… …resulted in the UA considering it was over its home position, regardless of its actual location, and landing. A software fix was completed on 6 June 2017, but this was not made available until the manufacturer’s software Version 3.7 was released on 8 January 2018. The operator did not have ready access to gain this software upload according to the AAIB, and even if they had the accident occurred just 10 days after this non-mandatory upgrade was issued....
read moreRCMP AS350B3 Left Uncovered During Snowfall Fatally Loses Power on Take Off
RCMP AS350B3 Left Uncovered During Snowfall Fatally Loses Power on Take Off On 17 January 2012, Royal Canadian Mounted Police (RCMP) Eurocopter AS350B3 C-FMPG, was destroyed and its pilot killed at Cultus Lake, near Chilliwack, British Columbia. History of the Flight According the Transportation Safety Board of Canada (TSB) final report, earlier in the day, the helicopter had deployed from Vancouver to a Canadian Dept of National Defence (DND) site at Cultus Lake. At 1145, the helicopter took off and carried out human external transportation system (HETS) training… HETS is a system used by the RCMP to transport personnel on a long line (about 100 feet) hanging below the helicopter. The flight was conducted during periods of intermittent, light snowfall. Approximately 35 minutes later, the helicopter returned to the landing site and was shut down so that the pilot could get some lunch and prepare for the afternoon’s training flights. When the helicopter was shut down it was not snowing, and the engine air inlet covers, which were on board, were not installed. During the lunch break, heavy snow started to fall and lasted for approximately 15 to 20 minutes. After lunch: At 1315, the pilot decided to cancel the remaining training and return to Vancouver. Since shutdown, there appeared to be a significant accumulation of snow on the helicopter; the snowfall, however, had by then diminished to very light or none at all. The temperature was approximately –10°C. After the helicopter was reconfigured for the flight to Vancouver, the pilot entered the cockpit and prepared for start-up. At the same time, 2 ground crew members removed the snow accumulation from the 2 front windscreens. At 1349, the pilot started the helicopter, and the snow was flung off the blades. A significant amount of snow remained on the upper surfaces of the fuselage and tail boom. After lifting off into a hover, the helicopter climbed to approximately 50 feet above ground level (agl), and slowly travelled up and forward about 260 feet in a straight line before hovering for about 30 seconds at a height of 80 feet agl. Soon afterward, there was a muffled bang and a puff of grey/white vapour from the exhaust area, and the rotor revolutions per minute (rpm) decayed immediately. At the same time, the customary and familiar sounds from the engine rapidly disappeared, and the regular slapping sound of the rotor blades quieted significantly. The helicopter began to descend, turned quickly to the right about 150°, pitched nose-down briefly, and then descended more rapidly. During the final moments of the flight, the helicopter descended almost vertically, colliding with the terrain in a nose-down, right-side-down attitude. In all, the helicopter had been running for about 3 minutes. The helicopter was destroyed, and the pilot, the sole person on board, was fatally injured. The Safety Investigation The investigation determined that the accident helicopter struck the ground with a vertical velocity of 16.4 metres per second (m/s), which exceeded the designed structural capacity of the airframe. Even after the landing gear skids absorbed about 2 m/s, the airframe experienced a vertical velocity of 14.5 m/s. Mathematical modeling of the helicopter structural deformation revealed that the impact load factors on the airframe were between 15 g and 20 g forward, and between 40 g and 50 g downward. Once the g-force attenuation limit of the pilot seat was reached, the g forces were then transmitted...
read moreHF of the Selection of Parking Brake Instead of Speed Brake During a Hectic Approach
Human Factors (HF) of the Selection of Parking Brake Instead of Speed Brake During a Hectic Approach (BMI Regional ERJ145 G-CKAG) The UK Air Accidents Investigation Branch (AAIB) has reported in their January 2019 Bulletin on a runway excursion accident at Bristol Airport to BMI Regional Embraer ERJ145 G-CKAG on 22 December 2017. The investigators explain that: Occupying the left seat was a captain-under-training, new to both the operator and the aircraft type [the Pilot Flying (PF) for that sector]. Occupying the right seat was a company training captain, who was the commander of the flight [the Pilot Monitoring (PM)]. The crew anticipated that a Category II approach would be required and planned accordingly. However, on arrival in the Bristol area the expected holding was cancelled and the approach timeframe thereby shortened. Also, the approach briefing was delayed until after the ATIS was available and was then interrupted several times. Thus, although not unduly rushed, the crew requested additional track mileage and the approach briefing was conducted with numerous interruptions. Despite this the pre-landing checks were completed, the approach was stable, the required visual references for landing were acquired and a normal touchdown was achieved. The graphic below shows some of the events during the approach: The comments about opening of the speed brake are highly relevant to subsequent events (as discussed below). The PF decided to deploy the speed brake to lose the excess height and announced: “speed brake coming on”. However, the speed brake parameter recorded on the FDR did not indicate that the speed brake had deployed. The AAIB note that in the 13 or so minutes shown: There was significantly more RT than shown due to the weather, and ATC vectoring and management of another aircraft with marginal capability given the runway visibility. There were also significantly more crew communications than shown relating to checklists, minima, alternate airports and other operational issues. On touchdown the aircraft de-rotated sharply and the PF… …noticed an unusually rapid de-rotation and then found he had difficulty in maintaining directional control despite using corrective rudder. The commander thought that the PF might be “riding the brakes”, a common error during training, and advised him to take his feet off the brakes. The PF, still unable to control the aircraft, attempted to use the steering tiller but when the commander noticed this he called out “no no don’t use the nosewheel steering”. The PF recalled afterwards that he had considered using asymmetric thrust but did not think he had moved the thrust levers. The aircraft ran off to the left side of the runway, at which point the commander realised the parking brake was on, and onto the grass, continuing for 120 m before coming to a halt. In the confusion on the runway after touchdown, the thrust levers had been advanced and as the aircraft stopped the PF, realising they were forward, closed them. The AAIB note that the throttle movement may have occurred inadvertently through an inadvertent coupled biomechanical reaction as the aircraft decelerated. Examination of the CVR and FDR confirmed that: The autopilot was disengaged at about 80 ft aal and the aircraft touched down on the centreline. The aircraft started tracking right of the runway centreline and opposite rudder was used. The aircraft heading swung to the left of the centreline, skidding approximately along the centreline… Right...
read moreIncorrectly Rigged B1900D Charlotte, NC, 8 January 2003: 21 Fatalities
Incorrectly Rigged B1900D N233YV, Air Midwest Flight 5481, Charlotte, NC, 8 January 2003: 21 Fatalities On 8 January 2003, Beechcraft 1900D, N233YV, flying Air Midwest Flight 5481, operated for US Airways Express, crashed into a hangar shortly during takeoff from Charlotte, North Carolina. Both flight crew members and all 19 passengers were killed. The Safety Investigation The NTSB report subsequently established that after takeoff, the pilots had also been unable to control the pitch of the aircraft. This was the aircraft’s tenth flight after a D6 check by a 3rd party maintenance organisation. The previous nine flights all involved fewer passenger loads and a more forward CG. The loss of control on the 10th flight was because: The aircraft was overloaded by 580 lb and had an aft centre of gravity that was 5% beyond limits. The elevator control system did not have the full range of nose-down travel, due to incorrect rigging that had occurred during a maintenance visit just over 24 hours prior to the accident. On the night of 6-7 January 2003, the aircraft had undergone a scheduled maintenance check that included checking the tension of the elevator control cables. The technician involved was performing this task for the first time and so was receiving on-the-job training from a inspector, despite the clear conflict of interest that the inspector would do the Required Independent Inspection (RII) on the task performed by the technician under his guidance. The inspector stated that he did not think he needed to closely supervise the technician because of he had previous flight control rigging experience. A relatively high proportion of personnel in the facility were under going On the Job Training (OJT). The Federal Aviation Administration (FAA) had identified “serious deficiencies” in the training procedures at the facility, but these had not been corrected. Finding that the cable tension was low, the technician performed only selected steps from the comprehensive elevator control system rigging procedure to increase tension using cable turnbuckles. Both the technician and inspector were under the misapprehension that the whole rigging procedure was not needed if merely tensioning the cables. However, the technician inadvertently restricted the amount of nose down elevator travel that was possible to about half of what should have been available. A properly conducted functional test should have caught this error, but one was not required at the time. NTSB Probable Cause and Safety Recommendations The NTSB determined the Probable Cause to be: The airplane’s loss of pitch control during takeoff. The loss of pitch control resulted from the incorrect rigging of the elevator control system compounded by the airplane’s aft center of gravity, which was substantially aft of the certified aft limit. Contributing factors were: Air Midwest’s lack of oversight of the work being performed at the Huntington, West Virginia, maintenance station Air Midwest’s maintenance procedures and documentation Air Midwest’s weight and balance program at the time of the accident the inspector’s failure to detect the incorrect rigging of the elevator system the FAA’s average weight assumptions in its weight and balance program guidance at the time of the accident the FAA’s lack of oversight of Air Midwest’s maintenance program and its weight and balance program. Among the safety recommendations were: Safety Recommendation A-04-004 to the FAA to perform “targeted surveillance and increased oversight of maintenance practices”. The FAA confirmed “the need for FAA maintenance inspectors to observe actual maintenance work being performed and to confirm that...
read moreBritish Midland Boeing 737-400 G-OBME Fatal Accident, Kegworth 8 January 1989
British Midland Boeing 737-400 G-OBME Fatal Accident, Kegworth 8 January 1989 At 19:52 on Sunday 8 January 1989 British Midland Boeing 737-4Y0 G-OBME took off from London Heathrow for Belfast. Thirty three minutes later 47 people on board would be dead in a crash near the Leicestershire village of Kegworth. Just 13 minutes after take off, while climbing through 28,300 ft, the outer panel of one of the No. 1 (i.e left hand) engine fan blades detached, causing compressor stalls, airframe vibration and a smell of fire in the cockpit. The AAIB determined that the fan blade failure was due to high-cycle fatigue due to fan flutter. Testing revealed that in order for this mode to occur, the engine needed to be at a full-power setting, in a high angle of attack attitude, and above an altitude of 27,000 feet. About eight seconds after the fan blade failure, the Captain took control of the aircraft and disengaged the autopilot. He looked at the engine displays but did not gain a clear indication of the source of the problem. He relied on his knowledge of the aircraft air conditioning system and the First Officer’s assessment of the Engine Instrument System (EIS) when diagnosing the problem. The Captain thought the smoke and fumes were coming forward from the cabin to the flight deck and was assuming most of the air in the cabin was supplied by the No. 2 (i.e. right hand) engine. This logic would have been reasonable for other aircraft he had flown but for the B737-400 a portion of conditioned air for the cabin came from the No. 1 engine. Furthermore, on both the B737-300 and -400 air from the No. 1 engine is feed directly to the flight deck too. The Captain said, “Okay, throttle it back” about 19 seconds after the failure, referring to the No. 2 engine which the Co Pilot had stated was showing the higher vibration indications. At 43 seconds after the fan blade failure, the Captain ordered the First Officer to, “Shut it down,” without specifically identifying which engine. This was initially delayed because they noticed the undamaged No. 2 engine was not displaying signs of failure. They tried several times to complete the Engine Failure and Shutdown Checklist but some attempts were interrupted by communications with ATC and with the airlines ops staff. Two minutes and 7 seconds after the failure, the No. 2 engine was finally shut down and the auxiliary power unit (APU) was started. The smoke in the cockpit cleared. The No. 1 engine Exhaust Gas Temperature (EGT) began to reduce. The No. 1 engine rotor speeds and fuel flow also stabilised. These all reinforced the belief they had correctly shut down the failed engine. When British Midland had taken delivery of their first EIS equipped B737 an EIS-equipped training simulator was not available. The display consists of primary engine instruments to the left and secondary instruments (such as vibration) to the right. In their accident investigation report the UK Air Accident Investigation Branch (AAIB) say that the failure indications encountered were “outside the [crew’s] training and experience” and: They reacted to the initial engine problem prematurely and in a way that was contrary to their training. They did not assimilate the indications on the engine instrument display before they throttled back the No. 2 engine. As the No 2 engine was throttled back, the noise...
read moreUSAF CSAR HH-60G Downed by Geese in Norfolk, 7 January 2014
USAF HH-60G Downed by Geese in Norfolk During CSAR Training: Bird Stike, 7 January 2014 After dark on 7 January 2014, US Air Force (USAF) Sikorsky HH-60G Pave Hawk 88-26109, of the 56th Rescue Squadron, at RAF Lakenheath, Suffolk, crashed in marshland near the village of Cley next the Sea, Norfolk, UK. The four crew were fatally injured. The aircraft, valued at $40.3 million was destroyed. The helicopter had experienced multiple bird strikes during a nighttime rescue of a simulated downed F-16 pilot as a check ride for 88-26109’s pilot. The Combat SAR training mission involved two HH-60Gs, a lead aircraft and the accident aircraft. Both crews were using night vision goggles. The aircraft departed RAF Lakenheath at 1733 Local Time. At 1804 88-26109 was flying east toward the Landing Zone (LZ) near Salthouse, behind and the the left of the lead aircraft, separated by about 0.3nm / 10 seconds, at approximately 110 KIAS and 110 feet above ground level. The 56th Rescue Squadron frequently used this LZ for similar training missions. The flight path went over the over the Norfolk Wildlife Trust’s Cley Marshes, a bird sanctuary established in 1926. This was not part of the original plan, but strong winds and a desire to avoid noise disturbance in the village of Blakeney, meant that in-flight the ‘initial point’, where the aircraft would orbit before the run in to the LZ, was shifted toward the marshes. A flock of geese, likely startled by the noise of the oncoming helicopters, took flight from Cley Marshes and struck the 88-26109. At least three geese penetrated the windscreen. These rendering the pilot and co-pilot unconscious. One hit the aerial gunner rendering him unconscious too. At least one goose hit the nose of the aircraft, disabling the Trim and Flight Path Stabilization systems. The types of geese involved weighed between 6 and 12 lb (2.7-5.4 kg). These are substantially above any rotorcraft certification requirement. The AIB don’t discuss the design and certification requirements of the H-60. According to a Swedish accident report the UH-60M Black Hawk can withstand a 1.8 kg bird at maximum speed up to c5,000ft. Part 29, for civil rotorcraft over 3,175 kg has a 1 kg bird strike requirement at maximum speed up to 8,000ft. This damage and injury resulted in a loss of control and the helicopter rolled left and it impacted the ground approximately three seconds after being struck by the birds. The lead aircraft returned and landed alongside. The UK Military Low Flying Handbook, available to the crews, states crews should cross coastlines at right angles and above 500 feet AGL to avoid bird strikes in this low flying area, but the AIB note this advice “did not support mission requirements”. The January 2014 UK MOD bird activity map indicated an area of low-bird activity over Cley Marshes. However, on 6 January 2014), the NWT counted a flock of approximately 400 various geese, along with other birds at Cley Marshes. A storm surge that affected the near-by National Trust Blakeney Nature Reserve in early December 2013 is believe to have caused several flocks of birds to relocate in the direction of Cley Marshes. The parent 48th Fighter Wing safety briefing for January 2014 instructed aircrew to assume a moderate en route bird risk (though one might argue that the final approach to a LZ would normally be ranked higher but for the very low en-route operating height), which these crews did. The crew’s pre-flight overall Operational Risk Management (ORM) rating for this...
read moreFatal Biplane/Helicopter Mid Air Collision in Spain, 30 December 2017
Fatal Biplane/Helicopter Mid Air Collision in Spain, 30 December 2017 On 30 December 2017 a collision occurred at Mutxamel (Alicante) aerodrome involving Bell 412SP helicopter EC-MMC and CASA 1131 Bucker Bü 131 Jungmann biplane N1950M. The Spanish accident investigation agency, the CIAIAC, explain in their safety investigation report that: The helicopter, operated by Babcock, was returning to the aerodrome after taking part in firefighting activities, while the biplane was on a private flight in the vicinity of the airport. According to the helicopter pilot he made position reports on the aerodrome frequency on several occasions and notified that he was on final approach to runway 30 at the uncontrolled airfield without having received any communication from any other aircraft. During the final approach, the rear of the helicopter was impacted, causing it to lose its tail rotor. As a result, the helicopter destabilized, although the crew managed to make an emergency landing in a level attitude and a clockwise yaw motion [from c 10m]. The biplane lost its right wings upon impacting the helicopter, as a result of which the pilot lost control of the aircraft, which crashed into the ground in an inverted position. The [biplane] pilot died after the accident as a result of the injuries sustained. The crew of the helicopter made an emergency landing and of its ten occupants, two were slightly injured. The rest were uninjured. According to the CIAIAC: The most likely cause of the accident was the failure of the pilot of the Bücker to detect the helicopter while on final approach to runway 30 at the Mutxamel aerodrome. The biplane was further back and in a higher position in the approach to land on the same runway. The investigators say the following factors contributed to the accident: The non-use of communications by the pilot of the Bücker; The failure by the pilot of the Bücker to fly the aerodrome pattern and flying acrobatic manoeuvres in the pattern Other Mid Air Collision (MAC) Safety Resources Aerossurance has previously published: Military Mid Air Collisions Military Airprox in Sweden North Sea S-92A Helicopter Airprox Feb 2017 Mid Air Collision Typhoon & Learjet 35 French TV Helicopter Accident in Argentina USMC CH-53E Readiness Crisis and Mid Air Collision Catastrophe Avoiding Mid Air Collisions: 5 Seconds to Impact AAIB Highlight Electronic Conspicuity and the Limitations of See and Avoid after Mid Air Collision a UK accident where a light single fixed wing aircraft descended into a helicopter. UPDATE 2 February 2019: A319 / Cougar Airprox at MRS: ATC Busy, Failed Transponder and Helicopter Filtered From Radar UPDATE 16 February 2019: Merlin Night Airprox: Systemic Issues UPDATE 12 May 2019: Alaskan Mid Air Collision at Non-Tower Controlled Airfield UPDATE 14 August 2021: Alpine MAC ANSV Report: Ascending AS350B3 and Descending Jodel D.140E Collided Over Glacier UPDATE 18 June 2022: Limitations of See and Avoid: Four Die in HEMS Helicopter / PA-28 Mid Air Collision Also: UPDATE 25 January 2019: Airbus Helicopters AS350B3 I-EDIC engaged in heli-skiing and Jodel D.140E Mousquetaire IV F-PMGV collided in mid air over the Rutor Glacier in Italy. Eight of the nine persons on board the two aircraft died. UPDATE 2 May 2019: TSB Canada report on a Piper PA-42 Cheyenne III and a Cessna 150. UPDATE 20 May 2019: US Army C-27/USAF C-130 Night MAC 1 December 2014: The Investigation attributed the collision to a lack of visual scan by both crews, over reliance on TCAS and complacency despite the...
read moreDisorientated Dive into Lake Erie
Disorientated Dive into Lake Erie On 29 December 2016 Cessna 525C (Citation CJ4) N614SB of Maverick Air, was destroyed when it impacted Lake Erie shortly after a night takeoff from runway 24R at the Burke Lakefront Airport (BKL), Cleveland, Ohio. The pilot and five passengers died. History of the Accident Flight According to the US National Transportation Board (NTSB), safety investigation report: The airplane entered a right turn shortly after takeoff and proceeded out over a large lake. Dark night visual conditions prevailed at the airport; however, the airplane entered instrument conditions shortly after takeoff. The airplane climb rate exceeded 6,000 fpm during the initial climb and it subsequently continued through the assigned altitude of 2,000 ft mean sea level. The flight director provided alerts before the airplane reached the assigned altitude and again after it had passed through it. The bank angle increased to about 62 degrees and the pitch attitude decreased to about 15 degrees nose down, as the airplane continued through the assigned heading. The bank angle ultimately decreased to about 25 degrees. During the subsequent descent, the airspeed and descent rate reached about 300 knots and 6,000 fpm, respectively. The enhanced ground proximity warning system (EGPWS) provided both “bank angle” and “sink rate” alerts to the pilot, followed by seven “pull up” warnings. The aircraft impacted Lake Erie. Analysis The NSTB hypothesise that: It is likely that the pilot attempted to engage the autopilot after takeoff as he had been trained. However, based on the flight profile, the autopilot was not engaged. This implied that the pilot failed to confirm autopilot engagement via an indication on the primary flight display (PFD). The PFD annunciation was the only indication of autopilot engagement. Inadequate flight instrument scanning during this time of elevated workload resulted in the pilot allowing the airplane to climb through the assigned altitude, to develop an overly steep bank angle, to continue through the assigned heading, and to ultimately enter a rapid descent without effective corrective action. A belief that the autopilot was engaged may have contributed to his lack of attention. The pilot had relatively low time on type having gained a type rating on three weeks earlier. The pilot subsequently completed a simulator-based recurrent training course at FlightSafety International on December 17, 2016. The pilot had accumulated a total of 56.5 hours in Cessna 525 airplanes. Of that time, 8.7 hours were as pilot-in-command which included the practical test. His most recent logged flight was on December 17 from Orlando International (MCO) to OSU. The pilot owned a Cessna 510 (Mustang) for about 2 years before purchasing the accident airplane. He had logged 372.9 hours total time in Cessna 510 airplanes. It is also possible that differences between the avionics panel layout on the accident airplane and the [C510] airplane he previously flew resulted in mode confusion and contributed to his failure to engage the autopilot. A comparison of the Cessna 525 systems and those of the airplane previously flown by the pilot, a Cessna 510, revealed that the autopilot engagement button on the Cessna 510 is located in a slightly different location on the Automatic Flight Control System (AFCS) panel. In the Cessna 510, autopilot engagement is indicated along the upper portion of the PFD similar to the accident airplane. In addition, an indicator...
read moreFinal Report Issued on 2008 B737 Bird Strike Accident in Rome
Final Report Issued on 2008 B737 Bird Strike Accident in Rome On 10 November 2008 Ryanair Boeing 737-8AS EI-DYG collided with a dense flock of starlings (typical mass 40-1o0 g) on short finals at Rome Ciampino. The Italian safety investigation agency, the ANSV, discuss this accident in a final report issued 20 December 2018. The crew spotted the birds and being aware of the relatively short 2207m runway, initiated a go-around around 100m from the threshold at approximately the same time as impacts occurred. The crew said these sounded like hailstone impacts. However, both engines were unable to deliver sufficient thrust, with N1 (fan speeds) dropping from 62% to 41%. The aircraft, with 172 persons on board, rapidly lost speed and height. The aircraft hit the ground about halfway down the runway, nose high in a near stall condition, on the main landing gear and the lower part of the rear fuselage. The left main landing gear collapsed and the left engine nacelle came into contact with the runway. There were 8 injuries, all minor. Investigators identified 86 bird impacts (on the radome, forward fuselage, wing leading edges, flaps undersides, engine nacelles and landing gear). While this damage would not have affected control of the aircraft, there was extensive bird debris on the stator and rotor blades of the CFM56-7B26/3 engines. Investigators identified 55 impact points on the number 1 engine fan and 30 on the number 2 engine fan. The fan blades themselves showed little damage. The investigators identified that both engines had repeatedly surged after the impacts, which they believed to have considerably exceeded those required for certification. ANSV Conclusions on Cause The accident has been caused by an unexpected loss of both engines thrust as a consequence of a massive bird strike, during the go-around manoeuvre. The loss of thrust has prevented the aircrew from performing a successful go around and has led the aircraft to an unstabilized runway contact. Contributory factors were: The inadequate effectiveness of bird control and dispersal measures put in place by the airport operator at the time of the accident; The captain decision to perform a go around, when the aircraft was at approximately 7 seconds from touchdown. This decision was significantly influenced by: The lack of instructions to flight crew concerning the most suitable procedures to adopt in the case of single or multiple bird strikes in the landing phase; The absence of specific training in the management, by the flight crew, of the “surprise” and “startle” effects in critical phases of the flight. They also explain that the elongated completion of the report was due to retirements and staff shortages. ANSV Safety Recommendations ANSV-12/1525-08/1/A/8 Addressees: EASA and FAA ANSV recommends to provide flight crews with guidelines and/or operational and training procedures, based on a careful assessment of the risks associated with the conduct of the aircraft in approach in case of birds encounter or single/multiple bird strikes. These guidelines should include the following topics: to discuss bird strike risks during take-off and approach briefings when operating at airports with known or expected bird activity; in case of single/multiple bird strikes in the final approach phase, if landing is assured, it is preferable to land maintaining the lowest engine power setting possible rather than carrying out a go-around procedure (in case of birds ingestion, especially a massive one, the engines damages can be greater at...
read moreInadequate Maintenance at a USAF Depot Featured in Fatal USMC KC-130T Accident
Inadequate Propeller Maintenance at a USAF Depot Featured in Fatal USMC KC-130T Yanky 72 Accident Maintenance issues at a US Air Force (USAF) depot featured in the loss of US Marine Corps (USMC) Reserve Lockheed KC-130T Hercules 165000 (callsign Yanky 72) and 16 lives when a propeller blade failed in flight over Itta Bena, Mississippi on 10 July 2017. The USMC Command Investigation determined that the accident was due to: …an inflight departure of the number four blade from the number two propeller. This propeller blade (P2B4) liberated while the aircraft was flying at a cruise altitude of 20,000 feet. This liberation of P2B4 is the first known occurrence of a circumferential fatigue crack initiating from a radial crack which had not grown to pass fully through to the outer diameter blade shank wall of a propeller produced by UTC Aerospace Systems (UTAS). [The liberated blade] sliced through the left (port) side of the fuselage, and impacted the interior of the right (starboard) side… This impact caused the skin of the aircraft to separate along the starboard side. The energy transferred from P2B4’s impact through the structure of the airframe also caused an overload condition of propeller three’s drive shaft. This resulted in its associated reduction gearbox assembly (RGA) failing and the separation of propeller three from the aircraft. Propeller three then momentarily embedded into the upper right section of the fuselage. After which, it continued over the aft starboard section of the fuselage and impacted the starboard horizontal stabilizer separating a significant portion of the stabilizer from the aircraft. As a result, the fuselage “explosively disintegrated into multiple pieces” says the investigation. Post-mishap analysis of P2B4 revealed that a circumferential fatigue crack in the blade caused the fracture and liberation. This fatigue crack propagated from a radial crack which originated from intergranular cracking (IGC) and corrosion pitting. This intergranular radial crack in P2B4 had grown to a total of 2.7 inches in length along the interior taper bore of the blade, extending 1.25 inches beyond the bushing. The radial crack had grown outward through 64 percent of the shank wall section until it was 0.45 inches from the outer diameter at the time P2B4 liberated on 10 July 2017. When the circumferential fatigue crack reached critical length the remainder of the blade shank structure failed in overload… The analysis also revealed the presence of anodize coating within the band of corrosion pitting and intergranular cracking on the blade near the origin of the crack. This finding proves that the band of corrosion pitting and intergranular cracking was present and not removed during the last overhaul of P2B4 at Warner Robins Air Logistics Complex (WR-ALC) in the fall of 2011. The investigation concluded that the failure to remediate the corrosion pitting and intergranular cracking was due to deficiencies in the propeller blade overhaul process at WR-ALC which existed in 2011 and continued up until the shutdown of the WR-ALC propeller blade overhaul process in the fall of 2017. In fact 12 of the 16 propeller blades on the accident aircraft “were determined to have: corrosion that existed at the time of their last overhaul at WR-ALC”. A US Navy (USN) engineering team conducted a ‘process audit’ of the WR-ALC propeller blade repair facility in August 2017. Their report concluded the US Navy requirements for propeller overhaul are different from the USAF requirements. The team...
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