ERJ-190 Flying Control Rigging Error
ERJ-190 Flying Control Rigging Error (UPDATED 25 June 2020 with Final Report) The Portuguese accident investigation agency, GPIAAF, issued a safety investigation update on 31 May 2019 on a serious in-flight loss of control event involving Aruba registered Air Astana Embraer ERJ-190 P4-KCJ that occurred on 11 November 2018, immediately after a C2-Check (1C + 2C + 6 year) at the OGMA facility at the Alverca Air Base, in Poartugal. This was a ferry flight back to Kazakhstan with 6 persons on board, not a maintenance check flight. The aircraft was landed safely but with structural damage sufficient to make this an accident in accordance with ICAO Annex 13. The crew had however encountered considerable difficulty controlling the aircraft, so much so they had debated ditching offshore. However, they regained a degree of control. After two unstabilised approaches, the crew landed runway 19L. The intended runway was 19R, but due to lateral drift they were forced to land on 19L. One passenger fell and suffered a minor injury. https://youtu.be/6n4mQvO4-tE Safety Investigation GPIAAF confirmed that an incorrect aileron control cable system installation had occurred in both wings during the maintenance check conducted in Portugal. GPIAFF note that: By introducing the modification iaw Service Bulletin 190-57-0038 during the maintenance activities, there was no longer the cable routing and separation around rib 21, making it harder to understand the maintenance instructions, with recognized opportunities for improvement in the maintenance actions interpretation. They comment on a problem with fault-finding that: The message “FLT CTRL NO DISPATCH” was generated during the maintenance activities, which in turn originated additional troubleshooting activities by the maintenance service provider, supported by the aircraft manufacturer. These activities, which lasted for 11 days, did not identify the ailerons’ cables reversal, nor was this correlated to the “FLT CTRL NO DISPATCH” message. Its possible, but not confirmed or discussed by GPIAAF, that the 11 days of fruitless fault-finding may have resulted in a delay and pressure to release the aircraft. GPIAFF comment that “deviations to the internal procedures” occurred within the third-party Part-145 maintenance organisation that “led to the error not being detected in the various safety barriers designed” in the process. They do not comment on what deviations occur, why they occurred or crucially how clear and practical those internal procedures were. They do say that the maintenance organisation is making changes. The investigators also suggest that the Type Certificate Holder review their documentation too. They also note that the error “was not identified in the aircraft operational checks (flight controls check) by the operator’s crew.” They add that: Amongst other issues, the safety investigation will look into the aircraft design and functioning, the crew procedures and human factors aspects raised, and will now focus on the maintenance procedures and applied aircraft technical documentation, as well as the human and organizational factors involved in the Part-145 service provider. Final Report (UPDATE 25 June 2020) The GPIAA final report was issued 24 June 2020. The OEM performed assessments on the aircraft primary structure showed exceedance of the limit loads, and according to the structural evaluation that was conducted based on 14CFR and RBAC Part 25 airworthiness requirements §25.305 (a), some degree of detrimental permanent deformation was found on the aircraft. The aircraft was considered beyond economic repair. The OGMA quality system was found to be “well structured and detailed”, however… Relevant gaps were…identified, namely on effective implementation and knowledge of these same procedures and standards by...
read morePA-34 Electrical Short Melted Rudder Cable
PA-34 Electrical Short Melted Rudder Cable (G-OXFF) Piper PA-34-220T Seneca V G-OXFF of Oxford Aviation Academy was about to enter the runway for takeoff at Oxford Airport on 2 November 2018 when the instructor noticed the rudder pedals felt soft and was “too easy to move”. The student confirmed they did not feel right, so they abandoned the planned flight and returned to the hangar for investigation. Safety Investigation The UK Air Accident Investigation Branch (AAIB) investigation report highlights the need for attention on EWIS (Electrical Wiring Interconnection Systems) of all sizes of aircraft: This Piper Seneca V was fitted with a Garmin 1000 fully integrated cockpit and avionic suite. The system is reliant on electrical power and has a standby battery to keep the system running in the unlikely event of a twin-generator and main battery failure. Inspection of the aircraft revealed the right rudder cable had chafed against the standby battery wiring and shorted to earth. The heat generated by the electrical short had melted through the steel-braided rudder cable. Safety Action This potentially serious risk to airworthiness was brought to the attention of the manufacturer, the CAA, EASA and the FAA. The CAA took immediate steps to inform owners and operators of similarly configured Piper Seneca V aircraft. The manufacturer has subsequently issued a mandatory Service Bulletin (No 1337) which gives instructions to reroute a portion of the emergency power wiring to improve the clearance from the rudder control cables. Safety Resources S-92A Flying Control Restriction on Wiring Loom C-130 Fireball Due to Modification Error UPDATE 1 June 2019: ERJ-190 Flying Control Rigging Error UPDATE 18 November 2020: Embraer ERJ-190 EWIS Production Quality a Factor in Fire UPDATE 27 December 2020: Fire-Fighting AS350 Hydraulics Accident: Dormant Miswiring UPDATE 8 February 2021: RCAF Investigate Defect on Newly Delivered CH-148 Cyclone (S-92) 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 moreLoose Engine B-Nut Triggers Fatal Forced Landing
Loose Engine B-Nut Triggers Fatal Forced Landing On 26 September 2017 Hughes (later MD) 369D SE-JVI was being used for power line inspection on behalf of energy company Vattenfall, by the First European Aviation Company when it suffered a sudden power loss and impact with the ground that killed one occupant History of the Accident Flight The Swedish Accident Investigation Authority, the SHK report that: The helicopter was equipped with a system to measure, photograph and present the status of the power line network and the surrounding terrain by means of advance data processing. The system allows for flying at a higher altitude and greater speed than in traditional power line inspection, where the operator carries out an optical inspection while flying close to the power line at low speed. The systems operator held a CPL-H and rather unusually (for a civil aircraft) was regarded as the aircraft commander and was acting as Pilot Monitoring. Shortly after take-off from Älvsbyn/Högheden Airport [shortly after refuelling after the first sector of the day], at a height of about 80 metres above the ground and a speed of 67 knots, they started to rapidly lose both altitude and speed. Twelve seconds later, the helicopter collided with the ground at the side of a grass field behind a building and near the edge of a forest. The helicopter sustained substantial damage, but no fire broke out. The systems operator was killed and the pilot was seriously injured. Examination of the accident site showed that the helicopter “had a descent angle of approximately 70 degrees, close to zero forward speed and very low rpm in the main rotor and tail rotor, combined with an exceptionally large coning angle of the rotor disk at some point during the sequence”. These findings indicated that the engine stopped supplying power during the flight. The technical investigation showed that a [B-nut] fitting to the gas generator fuel control unit had come loose during the flight…. The relatively low speed and altitude, in combination with a heavily loaded helicopter, meant a briefer autorotation than those practised during training. The Pilot Flying also had just 67 hours on type (though the system operator had 698 hours on type). For this reason, the crew did not reach the landing site without utilising the available rotor rpm at an early stage, which lead to a hard collision with the ground. The high vertical speed of some 2000–2400 feet per minute (10–12 m/s) and low or zero forward speed at the time of the collision means that the helicopter was subjected to forces which exceeded what it was designed [for]. Also of note: …it took 1 hour and 40 minutes before the crashed helicopter was located by the rescue services and medical resources arrived at the scene, despite the helicopter’s ELT starting to transmit at the time of the accident. Investigation Examining the Rolls-Royce 250 engine: …it was discovered that the pipe that supplies reference pressure (the ‘reference pipe’) from the engine compressor to the free turbine regulator and the fuel control unit had come loose from its fitting. The threads of the pipe nut and the fitting were intact, which indicates that these had come apart prior to impact. The investigation noted that another pipe nut in the same pipe system was also loose, but it had not been completely dislodged. The last known maintenance on the...
read moreSurvey Aircraft Fatal Accident: Fatigue, Fuel Mismanagement and Prior Concerns
Survey Aircraft Fatal Accident: Fatigue, Fuel Mismanagement and Prior Concerns (C337A N5382S) On 17 May 2008 Cessna 337A Super Skymaster, N5382S on a marine mammal survey flight, was destroyed when it impacted trees near Eagles Nest Airport, West Creek, New Jersey, during a fuel related diversion. The pilot and one of the three passengers onboard were killed. The US National Transportation Safety Board (NTSB) determined the probable cause to be: The pilot’s departure with insufficient fuel for the planned flight, and his improper in-flight fuel management, which resulted in a total loss of power in both engines due to fuel starvation. Contributing to the accident was the pilot’s fatigue, which was precipitated by his work activities during the days just prior to the accident flight. Concerns had been raised about the pilot and the operation just days before. This fatal accident highlights the importance of doing a proper due diligence and having independent aviation expertise available when contracting for special mission support. A law suit brought by one survivor was settled out of court. Background and Previous Concerns According to the NTSB safety investigation report, the aircraft was operated by Ambroult Aviation, wholly owned by the accident pilot. The aircraft “was one of several owned and operated by the pilot, who flew many of the missions, and conducted most of the maintenance. Most missions were various types of survey flights”. The accident pilot was according to a colleague “very intelligent but disorganized, and not a good businessman”, “struggling to stay financially afloat”, “very paranoid” of FAA inspectors and “reticent to make any distress calls”. A local mechanic reported that the pilot/mechanic’s “maintenance record keeping was poor”. Investigators were unable to located the full set or aircraft technical records. The most recent annual inspection recorded was dated 25 June 2002. The battery for the emergency locator transmitter bore a “replace by” date that was four years prior to the accident. The pilot’s most recent flight review was successfully conducted on 24 February 2008. As he didn’t have his log book with him the certificated flight instructor completed the endorsement on the back of a business card. The pilot’s log books were never found. For this contract: The three passengers were employees of an environmental services company [Geo-Marine] that was contracted [by the State of New Jersey] to conduct aerial surveys of marine mammals [in areas intended for offshore windfarm development]. …the survey area extended approximately 80 miles north-south along the New Jersey shoreline, and extended approximately 20 miles east over the Atlantic Ocean. Each monthly survey consisted of flying 30 numbered course lines, called transects, to cover the entire survey area. The contract between the environmental services company and the State of New Jersey required that the FAA be contacted “to determine flight restrictions in the area” of the survey, and that the survey flights were to be conducted at an altitude of 500 feet. While 14 CFR Part 91.119 permitted operation at altitudes less than 500 feet over open water, a waiver was required for the operator to fly less than 500 feet from any person, vessel, vehicle, or structure. No records of the operator contacting the FAA for flight restrictions were located, and the operator did not contact the FAA for any waivers. Consequently, this reduced the likelihood that the operator’s aircraft, records or personal qualifications would be inspected or reviewed by the FAA. Each...
read moreAlaskan Mid Air Collision at Non-Tower Controlled Airfield
Alaskan Mid Air Collision at Non-Tower Controlled Airfield On the afternoon of 5 August 2016 Cessna 210 N1839Z and de Havilland Canada DHC-2T Beaver N30CC, collided in midair while landing at Wasilla Airport (PAWS), Alaska. The flight instructor and student pilot on board the Cessna 210 sustained minor injuries. The pilot and passenger of the Beaver were uninjured. According to the safety investigation report of the US National Transportation Safety Board (NTSB): The flight instructor and student pilot on board the Cessna were conducting practice takeoffs and landings using the airport’s published right-turn traffic pattern. At the same time, the…single-engine de Havilland airplane departed an airport 5 miles to the north, proceeded to the airport and turned onto the final leg of the traffic pattern for landing. The instructor on board the Cessna reported that, during their fourth landing, just as the student began the landing flare, there was a sudden loud noise, and the airplane abruptly nosed down and impacted the runway. The instructor reported that he did not hear or see the other airplane before the collision. The pilot of the de Havilland reported that neither he nor his passenger heard any radio transmissions from the Cessna, and they did not see the Cessna in the traffic pattern until impact. The pilot stated that, about 70 ft above the runway surface, the Cessna overtook the de Havilland from directly above, impacting the propeller. The pilot was able to maintain control and subsequently landed the airplane. A postaccident examination of both airplanes, revealed signatures consistent that the initial impact sequence was between the empennage of the Cessna and the propeller assembly of the de Havilland. Day visual meteorological conditions prevailed in the area, and neither airplane was in communication with air traffic control; the airport was not equipped with a control tower. A recording of transmissions made on the airport’s common traffic advisory frequency (CTAF) revealed that, although the Cessna instructor made radio transmissions throughout the first three traffic patterns; no radio transmissions were heard from the Cessna pilots during the final (accident) traffic pattern. The de Havilland pilot stated his airplane’s position before entering the traffic pattern and again on the final leg announcing his intent to land. Postaccident examination and testing of the two radios in the Cessna revealed no mechanical anomalies. Additionally, the radios in both airplanes were tuned to the correct frequency for the airport CTAF. The Cessna instructor reported the he made a radio transmission during the final traffic pattern. It was undetermined why no CTAF radio transmission from the Cessna was heard on the CTAF recording for the accident traffic pattern. The NTSB comment that: Neither airplane was equipped with an Automatic Dependent Surveillance – Broadcast (ADS-B) system or cockpit display of traffic information. Had both airplanes been fully equipped with an ADS-B system capable of both transmitting and receiving position data and issuing traffic alerts via cockpit display, each pilot would have been alerted to the presence of the other airplane, and it is likely that the collision would have been avoided. The see-and-avoid concept requires a pilot to look through the cockpit windows, identify other aircraft, decide if any aircraft are collision threats, and, if necessary, take the appropriate action to avert a collision. There are inherent limitations of this concept, including limitations...
read moreNear B777 CFIT Departing LAX (0.3 mi H / 0 ft V)
Near B777 CFIT Departing LAX (0.3 mi H / 0 ft V) According to the US National Transportation Safety Board (NTSB) investigation report issued 7 May 2019 a “near controlled flight into terrain (CFIT) incident occurred near Mt. Wilson, California, when a Boeing 777-300 departing Los Angeles International Airport (LAX) was instructed to turn left toward rising terrain after departure from runway 07R”. The serious incident occurred on 16 December 2016, at about 01:25 local time when Eva Air flight 015, a B777-300, registration B-16726, was departing LAX for Taipei with 353 people on board. Air traffic control services were provided by the Federal Aviation Administration (FAA) Southern California Terminal Radar Approach Control (SCT TRACON). The NTSB explain that: Due to weather in the area, LAX was operating in an east flow configuration with aircraft departing to the east. The Boeing 777-300 pilot contacted the SCT controller and was given an initial climb to 7,000 feet. A short time later, the SCT controller instructed the pilot to turn left to a heading of 180 degrees which required a left 270 degree turn. The turn resulted in the aircraft turning toward rising terrain and back toward the airport; normal procedures in an east flow would have been for a right turn to a heading of 180 degrees. While in the left turn, the pilot requested a high speed climb which resulted in the aircraft accelerating beyond the 250 knot LAX class B speed restriction and required additional airspace in order to complete an assigned turn. After recognizing the aircraft was in a left turn, the SCT controller issued the crew a right turn to a heading of 180 degrees. As the aircraft began to turn right, the air traffic controller instructed the crew to expedite the turn due to recognizing a developing proximity issue with another aircraft that had departed from LAX. The air traffic controller stopped the climb of the B777-300 and issued a left turn to a heading of 270 degrees. These turns in quick succession, combined with the speed of the aircraft, resulted in the flight tracking northbound toward rising terrain. A request was made through the Taiwanese Aviation Safety Council [ASC] for the Enhanced Ground Proximity Warning System (EGPWS) data from the aircraft. The EGPWS data provided to the NTSB indicated that at 0924:30, the EGPWS system generated four “caution terrain” alerts to the aircrew. At 0924:41, there were four more “caution terrain” alerts provided to the aircrew. At 0924:49, the EGPWS system generated a “pull up” alert that lasted until 0924:56. [There is no indication the FDR was downloaded, though this may be due to a delay launching the investigation. The crew reported they responded by increasing the rate of climb]. The closest lateral and vertical proximity between the airplane and terrain/obstructions was about 0.3 miles and 0 ft, respectively, which is less than the minimum separation requirements. This incident was reported through the submission of a Mandatory Occurrence Report (MOR) completed on December 16, 2016, by the SCT Operations Manager. The FAA did not initially consider this worthy of internal safety investigation: On December 16, 2016, the FAA Western Service Area (WSA) QC staff contacted the FAA Compliance Services Group (CSG) and spoke with the on-call specialist about the incident. After a review of the incident using...
read moreG200 Leaves Runway in Abuja Due to “Improper” Handling
G200 Leaves Runway in Abuja, Nigeria Due to “Improper” Handling On 25 January 2018 Nestoil Gulfstream 200 (G200) 5N-BTF suffered a loss of control and runway excursion during the landing roll at Azikiwe International Airport, Abuja. The aircraft came to a stop at the right shoulder of runway 22 with the right main landing gear broken off. Investigators report this was due to the premature use of nose wheel steering, exaggerated by both crew making inputs. The Accident Flight According to the Accident Investigation Bureau Nigeria (AIB Nigeria) safety investigation report: The aircraft was operating a charter flight, on an Instrument Flight Rules (IFR) flight plan, with four passengers and three flight crew members onboard. The Captain was the Pilot Flying (PF) and the Co-pilot was the Pilot Monitoring (PM). [A third pilot, described as an observer, was also in the cockpit]. The aircraft was vectored for an ILS approach runway 22. The AIB confirm the approach was stabilised: At 15:18 h, the aircraft touched down slightly left of the runway centre line. According to the PF, in the process of controlling the aircraft to the centre line, the aircraft skidded left and right and eventually went partly off the runway to the right where it came to a stop. In his report, the PM stated that on touchdown, he noticed the aircraft oscillating left and right as brakes were applied. The oscillation continued to increase and [the aircraft] eventually went off the runway to the right where the aircraft came to a stop, partially on the runway. …the thrust reversers were not deployed and therefore did not affect the controllability of the aircraft. The aircraft fuselage was in one piece, but the [right main] landing gear assembly was detached. The nose landing gear tyres were abraded crosswise and the right inboard main wheel tyre was found deflated. The ATC immediately notified the Aircraft Rescue and Fire Fighting Services (ARFFS), Approach Radar Control and other relevant agencies about the occurrence. All persons on board disembarked normally with no injuries. The Safety Investigation Investigators concluded that: …the skid marks on the runway indicated that the aircraft steered in an S-pattern continuously with increasing amplitude, down the runway. On the last right turn, the aircraft exited the right shoulder of the runway, the right main wheel went into the grass and on the final left turn, the right main landing gear strut detached from its main attachment point after which the aircraft finally came to a complete stop on a magnetic heading of 160°. On examining the main wheel tires, no flat spots were found, therefore the effects of locked wheels, either before landing or during the landing roll, on this incident, can be ruled out. The AIB note that: The PM reported taking over control at the latter part of the landing roll when he saw that the aircraft was out of control. The PM did not announce taking over control, so both pilots were probably having inputs on the rudder pedal and brakes at the same time, counteracting each other and making the situation worse. FDR and CVR data were not available to determine when the PM took over control and to differentiate which pilot was doing what. The PM also cautioned the PF not to use the Nose Wheel Steering (NWS). During the post incident interview, the PF...
read moreDitching of Bristow S-76C++, Off Nigeria, 3 February 2016
Ditching of Bristow S-76C++, Off Nigeria, 3 February 2016 On 3 February 2016, Bristow Helicopters Nigeria Sikorsky S-76C++ 5N-BQJ ditched while en route from the deepwater ExxonMobil Erha Floating Production Storage Offloading (FPSO) vessel to Murtala Muhammed Airport Lagos. Accident Flight The Accident Investigation Bureau Nigeria (AIB Nigeria) say, in their safety investigation report (issued 25 April 2019), that on the outbound flight the Captain was the Pilot Flying (PF) while the First Officer was Pilot Monitoring (PM): A few minutes into the [outbound] flight, the Captain observed an unusual vibration of the aircraft and made a remark about this to the First Officer. About fifteen minutes later, the crew also reported that the Digital Auto Flight Control System (DAFCS) and TRIM FAIL lights illuminated twice and were reset. The No.1 autopilot decoupled on both occasions. Also…a passenger seated in the middle row reported perceiving a burning smell. The aircraft (MSN 760656 not 76056 as stated early in the AIB report) continued to its destination. On the Erha helideck the Captain “conducted visual checks but could not ascertain the source of the burning smell”. At 09:50 h, 5N-BQJ departed Erha FPSO for Lagos on the second leg of the flight with nine passengers and two crew on board, the First Officer was the PF; estimating LAG 10:40 h and endurance of one hour plus thirty-five minutes maintaining an altitude of 3,000 ft above mean sea level (AMSL). Fifteen minutes into the flight, there were repeated illuminations of ‘TRIM FAIL’ and Digital Automatic Flight Control System (DAFCS) indications. The Emergency Operating Procedure (EOP) was consulted and it recommended that the helicopter be flown hands and feet on the control. At 10:08 h, about 75 NM from LAG, initial contact was made with Lagos Approach. The Pilot Flying (PF) complained of the collective being heavy and the autopilot decoupling. There was loss of power, high rate of descent and decreasing altitude. The Captain observed a slight turn to the right and asked the PF to check heading and the PF reported that there was problem with the compass. The instrument readings were inaccurate and inconsistent, and the aircraft started drifting to the right. At about 66 NM on radial 145º from LAG, the Captain made a distress call “MAY DAY, MAY DAY, MAY DAY” on the Approach frequency. Afterwards, the aircraft stabilized at an altitude of 1,500 ft AMSL on a NE-E heading and the Captain briefed the passengers that they would have to ditch the aircraft. At about 10:19 h, 5N-BQJ made a controlled landing on water at approximately 77 NM on radial 139º of ‘LAG VOR’. The Emergency Flotation System (EFS) deployed. The Co Pilot stated: The [external] life-raft on the left was not fully deployed. This led to most passengers and crew utilizing the life raft on the right side. All 11 POB exited the aircraft without any injury. They were picked up by the Sea Trucks Group craneship Jascon 25. The aircraft subsequently over turned. Analysis The AIB note that: This aircraft was equipped with a dual DFZ-760 DAFCS systems that combines autopilot and flight director functions and requires synchronized heading input from the compass control among other inputs. With the compass control panel SLAVE-FREE switches set to SLAVE, the gyro is slaved to the earth’s magnetic field to provide accurate heading information to the pilot’s and co-pilot’s EHSI [Electronic Horizontal...
read moreUSAF UH-1N SAR Helicopter Hoist Training Accident
USAF UH-1N SAR Helicopter Hoist Training Accident On 27 April 2011, a USAF Bell UH-1N, 69-6603 of the 512th Rescue Squadron, 58th Special Operations Wing, Kirtland AFB, NM was performing hoist training when it was destroyed in an accident. The Accident Flight This accident was during an initial instructor flight engineer check ride. According to the USAF Accident Investigation Board (AIB) report: The training site was at 5382 feet AMSL, c 11ºC and wind was c 12 kts gusting 20 kts. The Evaluating Flight Engineer was controlling the up-limit switch on the hoist to simulated a malfunction. The student Flight Engineer tried several fault finding options. During this time an undetected aircraft drift forward and left occurred, positioning the aircraft 5 to 10 feet west of a discarded 2060 lbs (934 kg) F-111 escape capsule. The crew had used this as a landmark at ‘Site 15’ within the Kirtland range. Once the student Flight Engineer identified the simulated malfunction was caused by activation of the up-limit switch they swiped the other Flight Engineer’s hand away from the switch. This allowed cable retraction to resume. The co-pilot however was however still making an input to the pilot’s hoist control switch, as had been requested as part of the fault finding, when the up limit switch was released. As a result, the hoist cable retracted inadvertently and a rescue device, called a ‘forest penetrator‘, on the end of the hoist cable, snagged on the capsule. The pilot flying instinctively pulled up on the collective and the helicopter entered a descending right turn while tethered to the capsule and impacted sloping ground just 3-5 seconds after the snag. Two crew members attempted to activate the cable cutter but this occurred only factionally before impact. The crew of four all suffered either minor or no injuries and the aircraft was partial-consumed in a post crash fire after they egressed. The Integrated Data Acquisition Recorder (IDAR), a type of Flight Data Recorder (FDR) and the Cockpit Voice Recorder (CVR) were both damaged. No data could be obtained from either of them. Analysis The normal trouble shooting sequence for up-limit switch failure has the pilot try his hoist control switch two steps after the flight engineer has already ensured the up limit switch actuator is not in the up position. In this case the first steps of the pendant failure troubleshooting sequence were executed followed by the first step for up limit switch failure. It was not confirmed the pilot had release his hoist control. This non-standard sequence resulted in an unanticipated full rate cable retraction, as the pilots’ controls operate at full rate only (unlike the variable rate from the hoist operators pendant). USAF AIB Human Factor’s Analysis The investigators applied the the DoD Human Factors Analysis and Classification System (DoD-HFACS) taxonomy based on the work of Wiegmann and Shappell. They identified 7 relevant factors: (1) SP007 Authorized Unnecessary Hazard (Level 2: Supervision) This is a factor when “supervision authorizes a mission or mission element that is unnecessarily hazardous without sufficient cause or need”: The F-111 capsule had been on Site 15 for over a decade. At one point aluminum sheeting covered all the openings, but several panel coverings were missing at the time of the mishap. Without these panels, the capsule was an entanglement hazard. Previous site surveys noted the F-111 capsule’s presence. Multiple members in the 512 RQS verified that the capsule was a frequently-used reference point for operations. (The...
read moreFAA Rules Applied: So Misrigged Flying Controls Undetected
FAA Rules Applied: So Misrigged Flying Controls Undetected (Maintenance Human Factors and Independent inspections) On 30 April 2018, Cessna 172M Skyhawk II, N9085H, crashed shortly after takeoff in Bermuda. The Accident Flight In their investigation report the UK Air Accidents Investigation Branch (AAIB) say: The flight was planned to consist of a number of circuits and landings to refamiliarise the pilot with the aircraft [after it] had undergone a prolonged maintenance input. As this was the aircraft’s first flight after maintenance, the pilot fully checked the flying controls and their range of movement during the pre-flight checks. On completion of the in-cockpit pre-flight checks, the pilot confirmed that the elevator trim was set to the correct position for takeoff by checking that the trim indicator was in the takeoff position. Shortly after takeoff the aircraft exhibited a tendency to pitch nose down despite the application of nose up trim. The pilot decided to terminate the flight… During the final approach, the pitch-down tendency increased to the point where the pilot was unable to maintain the glidepath. The aircraft struck the ground approximately 15 metres from the runway threshold. The aircraft received significant damage and the pilot had minor injuries. N9085H was operated and maintained by a Bermuda-based organisation, holding [Bermuda Civil Aviation Authority] BCAA approvals for the continued airworthiness and maintenance of several aircraft. Prior to the leasing of N9085H, the BCAA had requested changes to the aircraft’s maintenance program, which were implemented, but responsibility for airworthiness regulatory oversight remained with the [Federal Aviation Administration] FAA and the maintenance of the aircraft was carried out by two FAA-licensed engineers. The Safety Investigation Given the pilot’s account, the investigators focussed on the aircraft’s flying controls. No defects were found within the aileron, rudder or elevator control circuits or the range and freedom of control surface movement. Photographs of the aircraft, taken immediately after the accident showed the elevator trim tab in a position which corresponded to a nose down trim position. The AAIB explain that: The Cessna 172 is fitted with a moveable trim tab on the right elevator. The trim tab is used to ‘trim’ the aircraft and allow it to be flown at various attitudes with minimal pilot control force. AAIB comment: Operation of the elevator trim system showed that the elevator trim tab moved in the opposite sense to the movement of the elevator trim wheel in the cockpit, with movement of the trim wheel to increase nose up trim resulting in movement of the trim tab to increase the aircraft’s tendency to pitch nose down. Detailed examination…confirmed that the trim tab drive chain was engaged on the actuator drive sprocket and that the chain guard was correctly fitted. Further examination showed that the elevator trim system cables were correctly routed through the fuselage but the section of the cables and chain in the horizontal stabiliser had been rotated through 180º, crossing the cables and drive chain. This resulted in the trim tab moving in the opposite sense to that commanded by the trim wheel input. The AAIB go on to say: …the aircraft’s maintenance records showed that the aircraft had undergone a prolonged maintenance input…during which the elevators, rudder and horizontal and vertical stabilisers had been removed to allow replacement of the horizontal stabiliser’s forward spar. Interviews with the mechanics involved…confirmed...
read more
Recent Comments