Insecure Pitch Link Fatal R44 Accident
Insecure Pitch Link Fatal R44 Accident During a post-maintenance check flight the main rotor separated from an R44 after a maintenance assembly error. A US National Transportation Safety Board (NTSB) report describes the fatal accident to Robinson R44 N3234U operated by Native Range Capture Services in Utah on 2 December 2014: The helicopter’s owner stated that, during a flight in the accident helicopter the month before the accident, the helicopter “had a bit of a vertical [vertical vibrations]”. The blades also had noticeable slop and movement in the pitch change link bolt attachment to the swashplate. During a 100-hour inspection, on November 2, 2014, at 582 hours of helicopter total time, the owner and pilot/mechanic recommended sending the blades out for rework. …the [red] main rotor blade pitch horn was replaced… …the owner hired the pilot-rated mechanic to install the blades and track them in a heavier configuration. A mechanic, who spoke with the pilot a few weeks before the accident, stated that they had a discussion about an elongated pitch change link attachment hole on the accident helicopter and how to address it. On the night before the accident flight, they spoke again; the pilot was having trouble tracking the blades on the accident helicopter. The pilot stated that he could not get the blades to track any better, and that he was trying to change the track with the trim tabs. During the accident flight witnesses heard “popping” or “banging” sounds, before seeing the main rotor and empennage separate from the helicopter. The NTSB state that: Witness statements and wreckage documentation were consistent with a main rotor blade striking the tail and subsequently, a mast bump, which resulted in the helicopter descending uncontrollably. The damage observed on the components of the main rotor system was consistent with an in-flight separation of the pitch change link for the red blade, with separation occurring at the location where the pitch change link attached to the swashplate. …a series of impressions corresponding to contact with threads on the red blade pitch change link attachment bolt were observed on the attachment hole bore through the swashplate in an area that should have only contacted the grip portion of the bolt. Thus, it is likely that the intact bolt separated from the attachment due to loss of the lock nut and palnut. According to manufacturer’s maintenance instructions, the attachment bolts used at the upper and lower ends of the pitch change links are NAS6605 series bolts. The locknuts for the NAS6605 series bolts should be fastened to a dry torque value of 240 lb-in ± 24 lb-in, and palnuts used on NAS6605 series bolts should be applied with a dry torque of 20 lb-in to 40 lb-in. During installation, the palnuts are installed over the top of the locking nut. Torque measurements were obtained on the locknuts installed on the three recovered pitch change link attachment bolts. All measured torque values were lower than that specified in the helicopter’s maintenance manual, indicating that the fasteners were improperly torqued before the accident. While torque for the missing attachment bolt could not be measured, the torque measured on the remaining pitch change link attachment bolts and witness marks on the attachment hole bore in the swashplate suggest that the bolt likely separated due to insufficient torque applied at...
read moreLeadership and Trust
Leadership and Trust Good leaders inspire trust. That’s one of the conclusions in a presentation Which difference do you want to make through leadership? (based on the work of Jim Kouzes and Barry Posner). Slide 6 comments on how trust increases as leaders follow through on their commitments: This is entirely consistent with our belief that leadership is not about hierarchy but is behavioural and is itself about influencing the behaviour of others. In the article: Getting beyond the BS of leadership literature it is also emphasised that: The focus on leadership should be about useful behavior rather than overly simplistic, and therefore fundamentally inaccurate, categorizations of people and personalities. Leadership can be shared: Rethinking Leadership “Businesses need a new approach to the practice of leadership — and to leadership development”. An example of both shared leadership and shared commitment can be seen in a discussion on safety leadership (and collaboration with a union leader to improve safety) the ‘Deepwater Horizon’ film reminds former Alabama Power CEO of lessons learned in tragedy. The utility CEO and a union leader had… …made a commitment to one another: we might disagree about many other things in the future, but we would never again disagree about safety. This was the first step in a long process towards mutual trust and respect. It took several years, but step by step we built a process and changed our “us versus them” culture. Tom Peters has said: “Leaders don’t create more followers, they create more leaders.” In a presentation So You Want to Create a Culture? Prof Edgar Shein, author of the highly influential Organizational Culture and Leadership, emphasised understanding the change you want to achieve, which in turn means understanding the problem you wish to solve or opportunity you wish to seize. Though Shein warns: But remember, those new elements won’t take hold unless they fit into your existing culture. Influencing others ultimately influences organisational culture which we discussed in our popular article The Power of Safety Leadership: Paul O’Neill, Safety and Alcoa and is further explored here: Building organisational leadership and culture to create trust during change. In Leadership for a just & interdependent culture John Nelson says: Overall, leaders must be the creators of communities of practice. Leadership is the start, the finish and the continuum to evolve its culture into a just and interdependent culture, and maintain it. In Talking leadership, Julia Fernando, Research Manager, Leadership Development at The King’s Fund, says of culture: The difficulty is that once a culture is set and norms are established, it can be hard to change the status quo. Changing a culture of fear and blame can therefore be difficult. Leadership plays a vital role in driving forward such changes… Though as we have showed previously, poor leadership can harm an organisation even quicker, and sometimes inadvertently reinforces that culture of fear and blame. One way to do that is by suffering from the Rule Illusion, a ‘rules bias’ where chronic risk aversion means establishing ever more complex rules that can be used against employees by organisations that don’t care about their employees. A recent post on the Science For Work blog sets out how important a sense of justice at work really is. Poorly enforced rules can easily undo all the other efforts. Yves Morieux of BCG commented in a TED Talk on business generally: If you think about it, we pay more attention to knowing who to blame in case we fail, than...
read moreNTSB Recommendation on JT15D Failure to Meet Certification Bird Strike Requirements
NTSB Recommendation on JT15D Failure to Meet Certification Bird Strike Requirements The US National Transportation Safety Board (NTSB) has issued a safety recommendation urging Transport Canada (TC) to take action to prevent catastrophic failure of Pratt & Whitney Canada (PWC) JT15D-5 engines following a bird strike or foreign object ingestion. This follows three NTSB investigations of what they call ‘incidents’ involving Beechcraft Beechjet 400A aircraft where failed fan blades breached engine cases and cowlings after bird strikes. The NTSB note these involved ingestion of “species well below the weight required for certification testing”. The ‘Incidents 31 July 2009 Beechjet 400A N679SJ immediately lost power from one engine after ingesting at least one bird during take off. The pilots successfully rejected the take off. All but one of the fan blades fractured and and that the inlet duct had separated from the front of the engine. Bird remains from a “1.5-2 lb” yellow-crowned night-heron were found on the runway and in the right engine. The NTSB say: Examination of the engine revealed that the engine spinner had separated from the engine due to the bird strike and entered the engine, resulting in the liberation of the fan blades and subsequent failure of the engine. The engine was certified to ingest a four-pound goose. However, the certification requirements in place at the time did not require the spinner to be tested during the certification process. The certification requirements were later updated to require testing of the spinner. At the time the NTSB determined that “contributing to the incident were the inadequate engine bird strike certification requirements in place at the time the engine was certified”. 13 March 2014 Beechjet 400A, N193BJ, was damaged following a bird strike shortly after take off from Greater Rochester International Airport, NY. The flight crew declared an emergency and safely returned to the airport. Extensive damage to the engine fan and inlet cowl occurred. The joint between the intake casing and intermediate casing failed. The compressor cowl had multiple holes and the right wing had an impact mark forward of the engine fan case. The bird remains were identified to be a herring gull. The average mass of this species is 1085g (2.39lbs). This aircraft is currently up for sale (minus the failed engine). 13 May 2014 Beechjet 400A N412GJ, suffered an engine fire following a bird strike during the take off roll, also at Sugar Land Regional Airport, Texas. The flight crew rejected the take off and successfully discharged both fire bottles. The fan blades had all fractured near the root. The nacelle had multiple penetrations. Afterwards fuel was found leaking from the engine nacelle and from a puncture in the right wing fuel tank. Recovered bird feathers were identified by the Smithsonian Feather Identification Lab as from a yellow-crowned night-heron. Their average mass is now qouted as “683g (1.51lbs)” by the NTSB. Certification History The JT15D-5 was certified under the standard current in October 1980 which stated that at take off power the engine must be capable of ingesting a 4 lb bird without catching fire (as happened in the third case), experiencing an uncontained failure (as happened in all three), generating loads greater than those ultimate loads specified or losing the capability of being shut down”. The NTSB say that: PWC provided a copy of Engineering Report No. 1105, “JT15D-5 Certification 4 Pound Ingestion Test.” The report...
read moreCessna 208 Forced Landing: Engine Failure Due To Re-Assembly Error
Cessna 208 Forced Landing: Engine Failure Due To Re-Assembly Error On 11 November 2016, Cessna 208B Caravan VH-TYV (‘TYV’) of Hardy Aviation departed from Darwin Airport, NT. On board were an instructor and trainee pilot who were to conduct an aircraft type re-familiarisation training flight. The Engine Failure and Force Landing In their investigation report the Australian Transport Safety Bureau (ATSB) say: After take-off at an altitude of about 500 ft above ground level (AGL), the instructor noted the climb speed reducing while the trainee continued to maintain the nose attitude for best angle of climb. At the same time, the instructor heard the engine lose power and a thin film of fuel partially obscured the windscreen. As the airspeed reduced to 60 kt, the instructor took control of TYV. They identified an area to the left of the aircraft as the most suitable for a forced landing and began a left turn towards that clear area at the target glide speed of 85 kt. As the aircraft turned, they assessed that sufficient height remained to continue the turn back towards Darwin Airport. At the completion of the turn, they selected 30 degrees of flaps to provide a short climb, which allowed the aircraft to clear two hangars and an area of trees. After clearing the hangars and trees, the instructor observed taxiway A in line with the aircraft and elected to land on the taxiway. The aircraft landed without further incident. Engineering Investigation & Analysis The ATSB report that: A post-incident examination of the engine found the number eight fuel nozzle locking plate missing. There was no damage to the locking plate mounts. The fuel nozzles had been replaced 86 flight hours prior to the incident, while the aircraft underwent maintenance in the United States, prior to importation into Australia. The ATSB determined that: The locking plate was probably not reinstalled when the fuel transfer tubes and nozzles were installed after replacement. The missing locking plate allowed the fuel transfer tube to slowly migrate out of the nozzle adaptor over the subsequent 86 flight hours. On the incident flight, the fuel transfer tube migrated far enough that fuel under pressure was able to escape from the nozzle adaptor. We have written about Critical Maintenance Tasks previously in an enduring popular article. Also see our articles: Fatal $16 Million Maintenance Errors Loose B-Nut: Accident During Helicopter Maintenance Check Flight USAF RC-135V Rivet Joint Oxygen Fire The Missing Igniters: Fatigue & Management of Change Shortcomings Misassembled Anti-Torque Pedals Cause EC135 Accident EC130B4 Accident: Incorrect TRDS Bearing Installation Misrigged Flying Controls: Fatal Maintenance Check Flight Accident UPDATE 16 April 2017: Insecure Pitch Link Fatal R44 Accident UPDATE 22 July 2020: NDI Process Failures Preceded B777 PW4077 Engine FBO ATSB Safety Message – Airworthiness This incident serves to underline the importance of ensuring all maintenance is completed entirely and correctly. [It also] demonstrates how the effects of incomplete maintenance can take a long period of time to manifest. The ATSB research report: An overview of human factors in aviation maintenance provides information on human factors errors made in the maintenance environment. Also see our articles: Professor James Reason’s 12 Principles of Error Management How To Develop Your Organisation’s Safety Culture Aircraft Maintenance: Going for Gold? Airworthiness Matters: Next Generation Maintenance Human Factors ATSB Safety Message – Flight Operations This incident also provides...
read moreDirector of Maintenance Pleads Guilty To Obstructing an NTSB Air Accident Investigation
Director of Maintenance Pleads Guilty To Obstructing an NTSB Air Accident Investigation The US Department of Transportation (DOT) Office of the Inspector general (OIG) has released the following statement: On March 10, 2017, David Esteves of Clearwater, Florida, pleaded guilty in U.S. District Court, Tampa, to obstruction of proceedings before departments, agencies, and committees. Esteves was the director of maintenance for Avantair, an airline fractional ownership and an on-demand air-charter business located at St. Petersburg-Clearwater International Airport. Esteves impeded the National Transportation Safety Board (NTSB) and FAA investigation of an accident involving the loss of an elevator from an Avantair aircraft. He instructed a contractor to remove parts from the aircraft and power up the plane, knowing that doing so would erase the cockpit voice recording and thus disrupt the investigation. A local press report states: While no one else has been charged in this case, federal documents note that Esteves was acting at the suggestion of his superiors at Avantair. Amy Filjones, spokeswoman for the U.S. Attorney’s Office in Tampa, said the federal investigation is ongoing. Esteves’ lawyer, Scott Robbins, said in court Friday that Esteves was cooperating with authorities. A U.S. magistrate judge did not set a sentencing date for Esteves, who was released on his own recognizance. In court, his lawyer said it was difficult to say whether his client would face prison time. AINonline report that: Under the plea agreement, Esteves is subject to a maximum sentence of five years in prison, a fine of $250,000 and three years of probation The Accident The accident involved Piaggio P.180 Avanti N146SL and occurred on 28 July 2012 (and is detailed in an NTSB report). The aircraft left Camarillo, CA at 06:15 local time, 23 minutes behind schedule intending to pick up passengers in San Diego, CA and convey them to Henderson, NV. The NTSB state: During the takeoff roll, the left elevator departed the airplane and was found off the side of the runway [at Camarillo a surprising] 3 days later. The crew arrived at the intermediate airport and quickly boarded the two waiting passengers. They did not perform an adequate preflight inspection and departed about 5 minutes behind schedule. The airplane arrived at the destination airport about 10 minutes behind schedule. The crew only noticed the left-hand elevator was missing from horizontal stabilizer in Henderson (after 2 sectors). The NTSB go on: An examination of the attachment nuts on the hinges of the right elevator found that they were finger tight. Examination of the hinge fittings on the left elevator and horizontal stabilizer revealed no mechanical damage or deformation to any of the components. Review of airplane maintenance records showed that an airworthiness directive (AD) had been complied with 54 days earlier, which involved both elevators being removed and then reinstalled. Materials laboratory examination of one of the right elevator attachment hardware bolt-nut combinations revealed that the self-locking nut exhibited run-on torque values well below the acceptable minimum torque. Based on the finger tight condition of the right elevator attachment hardware and the lack of any mechanical damage to the hinge fittings of the left elevator and stabilizer hinge structure, it is likely that all four sets of attachment hardware for both elevators were not properly torqued during the AD maintenance 54 days earlier. Additionally, 26 days before...
read moreHeli-Expo 2017 Photo Report
Heli-Expo 2017 Photo Report News from HAI Heli-Expo 2017 in Dallas, Texas: 17,788 people attended the show. A record-setting 322,800 sq feet of floor space was used with 731 exhibitors and 62 aircraft on display. Turnout was over 25% up on 2016 (though that is only to be expected after the off piste location of Louisville, Kentucky last year), with a good take up of exhibition space which some attendees saw as a sign of developing market optimism. All photos © Aerossurance unless otherwise stated. Bell FCX01 The big unveiling on the first morning of the show was the Bell FCX01, revealed by Bell CEO Mitch Snyder. Less a mock-up of a planned helicopter and more a ‘concept helicopter’, that is never intended to fly but which highlights possible future innovations, the FCX01 features proposed technologies that include: Hybrid propulsion, with an electrically powered ‘cross-flow fan‘ anti torque system Single pilot augmented reality cockpit (similar to that originally envisaged for the Airbus Helicopters X4, now the H160) with fly-by-wire as used on the 525 Variable geometry blade tips Unconventional landing gear MD Helicopters MD Helicopters also revealed their 8 seat 2.5t MD6xx helicopter with a four bladed tail rotor. They also described this as a ‘concept’ helicopter, though perhaps more a sign that they are yet to commit to development than a sign of radical innovation. Airbus Helicopters Airbus Helicopters H125 (nee AS350B3) a US Assembled Helicopter Leonardo Leonardo hinted at a new light twin (an AW209) and discussed a reengined AW009. They exhibited a HEMS AW119Kx, a winch equipped HEMS AW169 and an AW189 in ERA Helicopters colours, the only oil and gas configured machine at the show. ERA is the AW189 launch customer (video). Marenco SKYe SH09 Swiss manufacturer Marenco continue with their certification programme of the 2.6t SH09, announcing an order from Alpinlift Helikopter. Hélicoptères Guimbal Cabri G2 The two seat Guimbal Cabri G2 continue to make headway in the GA sector. Gear manufacturer ZF exhibited elements of the Cabri G2. Sikorsky S-92A Sikorsky exhibited a colourful SAR S-92A destined for the South Korean Coastguard. The aircraft on display was the Korean SAR organisation’s second S-92A. Tragically after the show, in which the centenary of the US Coast Guard was marked by both Sikorsky and Airbus, an Irish Coast Guard S-92A was lost during a SAR mission. At the show Heli-One, part of CHC, announced the availability of an external vision system for the S-92A. The baseline installation has cameras that focus on the engine and cargo ramp operations. The engine view provides live monitoring for smoke or abnormal operation, while the cargo door view offers pilots visual vantage points to aid ground operations. The enhanced solution adds two additional cameras attached to the hoist and cargo hook that can provide video during lifting operations. The cameras function effectively even in low light conditions. A video recorder with audio is also part of the enhanced package. The camera feeds can be shown on any of the five multifunction display units on the cockpit and pilots can easily toggle between views. This is not the only source of such cameras. Bristow have an installation on the HM Coastguard helicopters as illustrated in this video from an Inverness SAR S-92A: https://youtu.be/PxXLcwuSwdw These systems would potentially address the external detection requirement in Control 4.2 of the Flight Safety Foundation (FSF) Basic Aviation Risk Standard for Offshore Helicopter Operations (BRASOHO). The contractible BARSOHO Safety Performance Requirements (SPR)...
read moreUnstable Approach Dash 8 Touches Down 450ft Before Threshold
Unstable Approach Dash 8 Touches Down 450ft Before Threshold The continuation of an unstable approach following a loss of visual reference led to a Jazz Aviation (dba Air Canada Express) Bombardier DHC-8-102, C-GTAI, contacting the ground short of the runway at the Sault Ste. Marie Airport, Ontario, on 24 February 2015. There were no injuries, but there was significant damage to the aircraft. The Transportation Safety Board of Canada (TSB) report explains that: While on approach to Runway 30, in conditions of twilight and reduced visibility due to blowing snow, the aircraft touched down approximately 450 feet prior to the runway threshold. Following touchdown, the aircraft struck and damaged a runway approach light before coming to a stop approximately 1500 feet past the threshold. The TSB say: An examination of over 500 similar flights on Jazz DHC-8-102s showed that company aircraft routinely fly decelerating approaches below the minimum stabilization height of 500 feet. If approaches that require excessive deceleration below established stabilization heights are routinely flown, then there is a continued risk of an approach or landing accident. TSB Findings as to Causes and Contributing Factors The company standard operating procedures require an approach speed of Vref + 5 knots; however, this is being interpreted by flight crews as a target to which they should decelerate, from 120 knots, once the aircraft is below 500 feet. As a result, the majority of examined approaches, including the occurrence approach, were unstable, due to this deceleration. Due to ambiguity in the guidance and uncertainty as to the required speeds during the approach, the crew did not recognize that the approach was unstable, and continued. On the approach, the pilot flying reduced power to idle to reduce the approach speed from 122 knots toward 101 knots at 200 feet above ground level. This steepened the aircraft’s vertical path. The rapidly decreasing visibility resulted in the airport environment and the precision approach path indicator lights becoming obscured; as a result, the steepened vertical profile went unnoticed and uncorrected. Although the loss of visual reference required a go-around, the crew continued the approach to land as a result of plan continuation bias. The terrain awareness and warning system did not alert the crew to the aircraft’s proximity to the ground once the aircraft was below 50 feet, possibly due to the rapid rate of closure. This lack of warning contributed to the crew not being aware of the aircraft’s height above ground. Due to the uncorrected steepened vertical profile, loss of visual reference, and lack of normal terrain warning, the aircraft contacted the surface approximately 450 feet prior to the runway threshold. TSB comment: Confirmation bias can predispose pilots to seek cues confirming the belief that any decision to continue an approach is the correct one. In other words, pilots on approach are more likely to seek, and therefore find, information that would lead them to believe that continuing an approach is a safe decision. In this occurrence, the speeds flown on approach were relatively close to the flight crew’s understanding of what was required for a stabilized approach. This may have led to confirmation bias, in that the crew may not have acknowledged the decelerating speed or loss of visibility, but rather chose to focus on the perception of stability. Their history of successfully continuing approaches once already below...
read moreDeadly Delay: GOM B206B3 Helicopter Night Accident 6 Feb 2017
Deadly Delay: GOM B206B3 Helicopter Night Accident 6 Feb 2017 The US National Transportation Safety Board (NTSB) has released preliminary information on a fatal accident involving Bell 206B N978RH of Republic Helicopters off the coast of Galveston Island, TX on 6 February 2017: The flight originated from the oil tanker Eagle Vancouver, anchored in Galveston Bay…and was en route to Republic Helicopters heliport (2TE1), in Santa Fe [TX]. This was the helicopter’s third flight of the day. It departed 2TE1 at 1404 and flew to the oil tanker Eagle Vancouver and landed at 1457. The two passengers, both employees of Societe Generalde Surveillance (SGS) deplaned and commenced their work on the tanker. Significantly: The helicopter was scheduled to depart the tanker about 1600 but was delayed for unknown reasons. The helicopter eventually took off at 1837 and was scheduled to arrive at 2TE1 at 1910. Sunset was at 1802. Hence, the return flight was at night and also breeched industry guidance to schedule landing 30 minutes prior to sundown. The last radio communication from the pilot to Republic Operations was at 1906, when he reported he had the lights of Galveston in sight. The helicopter was equipped with a Blue Sky Global Positioning System (GPS) tracking system. The last data point from the Blue Sky system was at 1906…about .27 miles from the Galveston Island coastline. Altitude was 494 feet and speed was 127 mph. The accident site was…in West Bay, between Galveston Island and the mainland, or 4.30 miles from the last data… One passenger was fatally injured. The pilot and a second passenger were seriously injured. The helicopter was destroyed. Additionally, the NTSB say: Instrument meteorological conditions (IMC) prevailed at the time of the accident. The wreckage was recovered on February 8. Examination disclosed no evidence of airframe or flight control malfunction or failure. Engine examination disclosed no anomalies. Despite one of its Bell 230s suffering a blade strike on the deck of a vessel in 2011, Republic still boasts of an accident free record (and that their pilot maintain instrument currency) on their website (as downloaded today): A further fatal Gulf of Mexico helicopter accident occurred on 27 February 2017, involving Westwind Helicopters Bell 407 N1371 (see NTSB investigation). See also: Helicopter Ops and Safety – Gulf Of Mexico 2015 Update UPDATE 11 December 2017: The NTSB determined the probable cause as follows: The pilot’s failure to recognize the flight had encountered instrument meteorological conditions at night, which resulted in an unrecognized descent and collision with water. NTSB say: The helicopter was equipped with a GPS SkyRouter fast tracking system that reports the helicopter’s position every 2 minutes. The last data point received from the GPS SkyRouter system was at 1906, when the helicopter was about 0.27miles from the Galveston Island coastline at 494 feet and 127 mph. Republic Helicopters An “Inactive” signal was received from the Blue Sky GPS by Republic Helicopters Operations 10 minutes after this last contact, or 1916, and the U.S. Coast Guard was alerted. Based on time and distance from the last data point to the accident location with an approximate helicopter speed of 120 mph, the time of the accident was computed to be 1909 …the moon was “Waxing Gibbous with 78% of the Moon’s visible disk illuminated. The moonlight would have likely been visible above the cloud tops. Below 3,000 feet...
read moreSmoke in Cabin: Anatomy of a Wash Rig Error
Smoke in Cabin: Anatomy of a Wash Rig Error The Irish Air Accident Investigation Unit (AAIU) has recently reported on a smoke in cabin event on Aer Lingus Airbus A320-214 EI-DVJ at Dublin on 3 October 2015. This was due to actions taken during an engine wash the previous evening. We focus on the maintenance human factors lessons. The Incident Flight The AAIU explain: Immediately after take-off from Dublin (EIDW), on an early morning scheduled passenger flight to Munich, Germany (EDDM), the Flight Crew detected an unusual odour in the cockpit. A short time later, the Cabin Crew reported that there were fumes in the aircraft cabin. Following an assessment of the situation, the Flight Crew declared a PAN (state of urgency) to Air Traffic Control (ATC) and donned their oxygen masks. The aircraft returned to EIDW, where a normal landing and taxi to stand were performed. Once the air bridge was in position, the forward passenger door was opened and the passengers disembarked the aircraft. The Operator reported that the smell/fumes in the cabin were such “that by disembarkation, many passengers had [their] mouths covered with items of clothing and handkerchiefs”. Post-event medical examination of the Flight Crew resulted in no adverse findings. The Flight Crew Members donned their oxygen masks and therefore were no longer breathing air from the air conditioning system. However, the Cabin Crew Members, similar to the passengers, were breathing cabin air throughout the event. Subsequent medical tests on the Cabin Crew Members also resulted in no adverse findings and, at the time of writing, there have been no reports of associated illness from any of the Crew Members involved or from the passengers. Maintenance History The AAIU say: A scheduled engine wash was performed on the aircraft when it was undergoing maintenance on the night before the occurrence. Both maintenance engineers (referred to by the AAIU as ‘Engineer A’, who had a company authorisation on the A320, and the assisting ‘Engineer B’) read the Aircraft Maintenance Manual (AMM) prior to commencing the task on the aircraft’s CFM56-5 engines. They were aware that using a corrosion inhibitor additive during an engine wash was not essential, but if it were not used the aircraft had to fly within 24 hours. They said it was decided to use it to cover any unforeseen event that could prevent the aircraft from flying within the 24 hour period. Unfortunately: Prior to the engine wash being carried out, one can, containing eight US fluid ounces (236.6 ml) of corrosion inhibitor, was erroneously added to each of the 115 l water tanks of the engine wash rig [it should have been added to the engine oil tanks]. The AAIU note that: Engineer B said…although he had performed the engine wash in the past, he had never used the corrosion inhibitor and before using the engine wash rig, which is fitted with two fluid tanks, he needed to re-familiarise himself with its operation by reading the instructional placards and booklet affixed to the rig…which detailed how to connect the lances of the rig to the engine and how to adjust the pre-charge pressures of the tanks and the rate of fluid flow. Before pressurising the rig for use, with the cans of corrosion inhibitor sitting on top of the wash rig and [with] “tank” in his mind, he checked...
read moreATR72 Cognitive Bias Leads to Control Problems
ATR72 Cognitive Bias Leads to Control Problems On 4 March 2016, ATR-72-212A (ATR72-500), G-COBO, operated Aurigny Air Services, the flag carrier of the Crown Dependency of Guernsey, suffered autopilot drop outs and unusually high forward pitch control forces on departure from Manchester Airport. The aircraft diverted safely to East Midlands Airport. The UK Air Accidents Investigation Branch (AAIB) became aware of the occurrence and recently issued an investigation report that discusses cognitive bias and the crew’s low exposure to icing conditions. Pre-Flight Preparations The AAIB say: The aircraft arrived at Manchester Airport from Guernsey and remained on the ground for more than an hour, while it was snowing and the temperature was 0ºC. While taxiing in, the crew’s perception was that light, wet snow was falling and melting on the taxiways, although some was lying on adjacent grass areas. In addition, the co-pilot could see no ice on the airframe or on the Ice Evidence Probe (IEP) when he actioned the after-landing checklist. At 0814 hrs, the commander looked at the static air temperature gauge and observed that it was indicating between 1ºC and 2ºC. He then commented “it doesn’t appear to be sticking…so I think we can get away without de-icing”, adding that he would “have a good look”. There was then a protracted delay before the aircraft could park, because another aircraft was being de-iced on their allocated parking stand. During this delay, the commander said he did not see any snow settling on the aircraft and suggested snow visible on other aircraft had probably accumulated overnight. The aircraft shut down at 0837 hrs, 23 min before it was scheduled to depart on a return flight to Guernsey. Aircraft handling companies at Manchester stated that all other commercial aircraft which departed on the morning of 4 March 2016 sought de-icing/anti-icing before start-up. The de-icing providers had difficulty coping with the demand for their services and some flights were delayed while others were subsequently cancelled. It was the commander’s belief that the air temperature was just above freezing (approximately 1ºC) and he thought the falling snow was melting on the aircraft. He could not see the top of the horizontal tailplane but, from the rear access step, he thought he saw most of the top of the wings and believed there was no frozen contamination. After completing his inspection he told the co-pilot, who had remained in the flight deck, that they could continue without de-icing. The co-pilot judged the commander’s inspection to be thorough because it took a long time and he accepted this decision. The Incident Flight The AAIB say: During the takeoff, the commander exerted less aft pressure on the control column, to rotate the aircraft, than he expected and maximum nose-down pitch trim was then needed to maintain the appropriate climb attitude. The autopilot was engaged four times but on each occasion it disengaged, as designed, and the commander had to apply continuous forward pressure on the control column to retain the desired pitch attitude, as the climb proceeded. Once at the cruising level, the commander decided he was having to exert excessive forward pressure on the control column and he elected to divert to East Midlands Airport (EMA). While descending, the aircraft flew out of icing conditions and the control difficulties dissipated. The crew assessed that ice contamination had caused...
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