First Eleven: Guidance for Designers on Maintenance Human Performance
First Eleven: RAeS Guidance for Design Organisations on Maintenance Human Performance The Royal Aeronautical Society (RAeS) Human Factors Group: Engineering (HFG:E) has published a short guidance document on 11 steps an aviation Design Organisation (DO) can take to “deliver safer, more effective and reliable aircraft through improved design for maintenance”. The RAeS say: Aircraft safety and in‐service maintenance performance can be significantly improved through integrating maintenance Human Factors (HF) principles into aircraft design… Research shows that many aircraft incidents and accidents are caused or contributed to by maintenance errors that are induced or aggravated by aircraft design and technical documentation. Improved, user‐centred design and documentation reduces maintenance error and its consequences. Many DOs already recognise…their products can be improved through applying HF principles to reduce in the probability and consequences of maintenance errors, reduce lifecycle costs and improve operational reliability / availability. However, research by the HFG:E suggests that identifying practical steps to realise these benefits remains a significant challenge for many DOs. Consequently, the ‘First Eleven’ guidance was developed over several years of engagement with DOs, air accident investigators and regulators to be a practical series of steps for a DO to fully integrate the best practices for maintainer-centric design. A First Eleven gap analysis is a practical way to identify opportunities for improvement. The RAeS say: These are the ‘First’ Eleven because striving for enhanced maintenance human performance should be a continuously evolving process. The full guidance document can be found here. Aerossurance is pleased to have sponsored the RAeS HFG:E conference on 12 May 2015 at Cranfield University on Human Factors in Engineering – the Next Generation (as well as its staff actively participating in the HFG:E since 2005). We see the First Eleven as one way that DOs can contribute to next generation solutions that enhance maintenance human performance. Aerossurance is pleased to support the Chartered Institute of Ergonomics & Human Factors’ (CIEHF) Human Factors in Aviation Safety Conference that takes place at the Radison Blu Hotel, East Midlands Airport, 7-8 November 2016. Our presentation will discuss the importance of HCD. UPDATE 2 March 2018: An excellent initiative to create more HCD by use of a Human Hazard Analysis (HHA) is described in Designing out human error HeliOffshore, the global safety-focused organisation for the offshore helicopter industry, is exploring a fresh approach to reducing safety risk from aircraft maintenance. Recent trials with Airbus Helicopters and HeliOne show that this new direction has promise. The approach is based on an analysis of the aircraft design to identify where ‘error proofing’ features or other mitigations are most needed to support the maintenance engineer during critical maintenance tasks. The trial identified the opportunity for some process improvements, and discussions facilitated by HeliOffshore are planned for early 2018. A systems approach in healthcare: UPDATE 24 October 2022: The Royal Aeronautical Society (RAeS) has launched the Development of a Strategy to Enhance Human-Centred Design for Maintenance. Aerossurance‘s Andy Evans is pleased to have had the chance to participate in this initiative. Aerossurance has extensive airworthiness, design assurance, certification, maintenance error management and human factors experience. For professional design / maintenance HF support you can trust, contact us at: enquiries@aerossurance.com Follow us on LinkedIn and on Twitter @Aerossurance for our latest...
read moreSafety Data Silo Danger – Data Analytics Opportunity
Safety Data Silo Danger – Data Analytics Opportunity We recently enjoyed reading The Silo Effect by Gillian Tett. Tett, who has a PhD in social anthropology, is a journalist and senior editor for the Financial Times. Some organisations are, often by design, divided into silos (by project or by functional specialism). Silos however can restrict who we talk to and how we share information. Such ‘structural secrecy’ was noted by sociologist Prof Diane Vaughan in her examination of the disastrous NASA Space Shuttle Challenger launch decision. Tett (who discusses her work in this podcast) argues that the observational discipline of anthropology can also identify the unspoken silos within a organisation (as well as society as a whole). From a safety perspective the most interesting case study comes in the book’s introduction, a case study that is less about anthropological observations and more about data collation and analysis. Fighting Fire with Data On 25 April 2011 a fire a 2321 Prospect Avenue in the Bronx claimed three lives. The property had been “illegally subdivided, leading city officials to pledge a crackdown on a practice that can impede fire-fighters and imperil lives” in the resulting furore. New York City had a team of building inspectors and they were not short of complaints to investigate. Each year they received 20,000 complaints on the nearly 1 million buildings and 4 million properties in their remit via the city’s 311 phone line (which receives 30,000 calls on a host of topics every day). However, only 13% of those complaints when investigated wre valid, wasting time and limited resources. Another city department, the fiercely independent New York Fire Department (NYFD) had overlapping duties and its own data, effectively an inaccessible silo, but key data turned out to be split between many city departments and databases. In May 2011 New York City Mayor Michael Bloomberg appointed Mike Flowers to head a new Mayor’s Office of Data Analytics (MODA) and create what some have called ‘The Mayor’s Geek Squad’ of data analysts. They started to develop a way to use data from multiple sources (not just Dept of Buildings and NYFD data) to prioritise attention on the most probable reports of illegal conversions. Flowers said: Before we started, we didn’t know what we knew. The analysts did more than look at data. They spent time with building inspectors and fire-fighters to understand more about illegal conversions and fires. Flower’s explains that what they then did was: …come up with a way to prioritize those [complaints] which represent the greatest catastrophic risk… In doing that, we built a basic flat file of all 900,000 structures in the city of New York and populated them with data from about 19 agencies, ranging from whether or not an owner was in arrears on property taxes, if a property was in foreclosure, the age of the structure, et cetera. Then, we cross-tabulated that with about five years of historical fire data of all of the properties that had structural fires in the city, ranging in severity. After we had some findings and saw certain things pop as being highly correlative to a fire, we went back to the inspectors at the individual agencies, the Department of Buildings, and the fire department, and just asked their people on the ground, “Are these the kinds of conditions that you see when you go in post-hoc, after this catastrophic event? Is this the kind of place that has...
read moreEC130B4 Accident: Incorrect TRDS Bearing Installation
EC130B4 Accident: Incorrect TRDS Bearing Installation The Accident Investigation Board Norway (AIBN) has recently reported on a serious incident involving Airbus Helicopters EC130B4 LN-ORR, operated by Helicopter Utleie (now trading as Fjord Helikopter) on 12 August 2014 when arriving at Rørvik Airport for refuelling. The Incident As the helicopter passed over the runway threshold at about 15-30 feet the helicopter started to yaw to the left: The commander quickly understood that he had no directional control, and chose to land the helicopter without engine power. The helicopter rotated twice around its own axis before it was landed on the runway. No injuries or damage occurred. AIBN say: The reason it did not have more serious consequences was because the commander quickly figured out that the tail rotor was not functioning, and he made the right decisions. …it was decisive for the outcome that the incident occurred over a flat surface. Had the tail rotor shaft fracture occurred at a less favourable moment, and over rugged terrain, the outcome of the incident could have been fatal. The Technical Investigation and Analysis An examination revealed that the riveted joint just behind the tail rotor drive shaft (TRDS) no. 1 bearing had fractured. The bearings on the TRDS had been replaced during scheduled maintenance 98 flying hours prior to the incident. AIBN say: It became evident that the position of the bearing in relation to the shaft did not comply with the Aircraft Maintenance Manual (AMM) requirements. The measured discrepancy was approximately 1 millimetre, whereas the maximum permitted value in the AMM is 0.1 millimetre. Lab examination showed the rivet holes had deformed and the six rivets had become worn over time. When the rivets came loose gradually, the load increased to such a point that fatigue fractures occurred in some of the rivet holes on the shaft. There were also signs of a ductile fracture in one of the rivet holes. Lab examination of the bearing “showed that the bearings balls had made an abnormal track in the outer race”. AIBN asked the technician who installed the bearing to demonstrate the measurement method for verifying the bearing’s position in “Bearing drive/Bearing flange”. The measurement demonstrated to AIBN did not comply with the method described in the helicopter’s AMM. The aircraft technician had worked alone on Helikopter Utleie’s helicopters for many years. Without having a community of colleagues for support, there may be a risk of developing sub-standard working methods. The technician, from a contracted Part 145 (see below), had incorrectly used the tailboom structure as the reference not the TRDS itself. The AIBN state the specific AMM task was “was fully understandable”. With condor and proactivity: Airbus Helicopters… concluded that the measuring method and adapter to attach the dial gauge to the tail rotor shaft should be emphasised more clearly in AMM, so there is a greater degree of reproducibility of the measurement results when replacing bearing no. 1. AIBN established that the bearing installation had not been subject to an Independent Inspection by a second person. The work on LN-ORR was carried out at the helicopter company base in Stryn. The technician carried out this work alone. In a best case scenario, he would have inspected his own work. This would have been an inspection based on his personal understanding of the procedure in AMM, which was incorrect as regards installation of bearing...
read moreTroublesome Tiedowns
Troublesome Tiedowns The US National Transportation Safety Board (NTSB) has recently reported on two cases in October 2015 were helicopters offshore suffered accidents after the tie-downs were not fully removed: Fish Spotting Helicopter, Pacific Ocean (B206, N1060C) On 21 October 2015 Bell 206B N1060C was being prepared for take-off from the 74m Fishing Vessel Majestic Sun off Christmas Island, Kiribati in the Pacific for a fish spotting flight. The NTSB say: The pilot of the helicopter reported that he entered the helicopter for takeoff while the mechanic removed the tie downs from the helicopter. The pilot reported that when he tried to takeoff, one of the [four] tie downs was still attached to the helicopter and the helicopter rolled to the right and impacted the helipad. The helicopter sustained substantial damage to the main rotor, mast, and tail boom. In this case it appears that the tie downs were applied to the floats and were removed after the pilot boarded the helicopter (not unreasonable for operation on a small moving deck). Oil and Gas Helicopter, Gulf of Mexico (PHI B407 N420PH) On 30 October 2015, N420PH, a Bell 407 of PHI, lost most of one rotor blade in an accident on an offshore installation in the Gulf of Mexico (WC167). The operator reported that: …the pilot and aircraft began the operational day at High Island A 264, an offshore platform located in the Gulf of Mexico. The pilot began his duty day at 06:25 CST. At 08:07 the aircraft departed the platform with the pilot and one passenger onboard destined for another offshore location, West Cameron 149 arriving at 08:41. The pilot dropped off his passenger and flew the aircraft with no passengers to another offshore location; West Cameron 167 arriving at 08:51 . The pilot shut down the aircraft and secured the main rotor system by attaching a rope to the forward left main rotor blade and tying the rope end to the left front skid cross tube. He then went inside the platform facility for slightly over 3 hours while waiting for a call to return to West Cameron 149 to pick up the passenger. The pilot received a call at approximately 12:15 instruction him to return to West Cameron 149 to pick up the passenger for further transportation as directed. The pilot went to the platform helideck were the aircraft was located and proceeded directly to the right-rear cabin door and placed his personnel bag in the aircraft. He then moved to the right-front cockpit door and placed additional personnel items in the aircraft in preparation for flight, then entered the aircraft using the same door and sat in the right-front pilot seat. He then proceed to start the aircraft and noted a few seconds after initiating the engine start the aircraft make an “unusual noise” and began to shake. He immediately secured the engine and completed aircraft shutdown. Upon exiting the aircraft he found one main rotor blade damaged by the rotation of the main rotor system with the tie down attached during the engine start. The NTSB comment: The Bell Helicopter 407 Rotorcraft Flight Manual lists the preflight check areas in Section 2 Normal Procedures. Regarding the exterior check, this manual states in part; 2-3-B-1. Fuselage – Cabin Right Side 1. All main rotor blades – tiedowns removed, condition. There is also a warning in this section that states, “Failure to remove...
read moreEASA and Ejection Seat Certification
EASA and Ejection Seat Certification The European Aviation Safety Agency (EASA) have issued a series of Certification Review Items (CRIs) for proposed Special Conditions and Equivalent Levels of Safety for a Part 23 ejection seat equipped tandem two-seat trainer aircraft to be certified in the Normal and Acrobatic categories. The CRIs consist of: CRI 102 Special Condition Canopy Fracturing System related to CS 23.805 (b) on emergency exits and CS 23.807 (b)(5) for abandonment. CRI 103 Special Conditions Ejection Seats related to CS 23.807 (b)(5) for abandonment. CRI 105 ELOS Emergency Provisions related to CS 23.785 (d) on single point release (when the ejection seat also includes leg restraint features for example) and CS 23.785 (h) on the occupants wearing a parachute (as opposed to being integral with the seat). CRI 106 ELOS HIC Compliance related to CS23.562 requiring testing and Head Impact Criteria (HIC) that are not compatible with an ejection seat. CRI 107 ELOS Lumbar Load Compliance related to CS23.562 requiring testing and lumbar load criteria that are not compatible with an ejection seat. The UK Military Def Stan 00-970 is the basis of much of the CRI proposals. The deadline for comment is 26 February 2016. EASA do not, as a matter of course, identify the specific aircraft type a CRI relates to. UPDATE 21 July 2016: EASA has validated the DGAC Turkey certification of the Turkish Aerospace Industries (TAI) TT32 HÜRKUŞ trainer using these SCs. Additionally, the UK military have recently committed to the purchase of three new aircraft types for the UK Military Flying Training System (UKMFTS). All three aircraft involved (the side by side two seat Grob 120TP turboprop, the Embraer EMB-500 Phenom 100 multi-engine business jet and the Beechcraft T-6C Texan II) have been civil certified. The UK Military Aviation Authority (MAA) has published a Regulatory Notice that explains how civil certification evidence can be used in a UK military type certification: MAA/RN/2015/15 (D TECH): Use of existing certification evidence as credit towards demonstrating compliance with the military air systems certification process. This includes the concept of identifying and assessing military deltas in usage and configuration relative to the civil certification. The T-6 is a development of the Pilatus PC-9 that won the US Navy managed Joint Primary Aircraft Training System (JPATS) competition in the 1990s. The tandem two seat Texan is also known as the Beechcraft 3000 and has been certified previously by the US Federal Aviation Administration (FAA). It is fitted with Martin-Baker zero-zero Mk 16 ejection seats. https://www.youtube.com/watch?v=cIwEG7opxtg&feature=player_detailpage The FAA TCDS for the Beechcraft 3000 states: This aircraft contains a canopy fracturing system and ejection seat system that was FAA approved based on the Equivalent Level of Safety provisions on 14 CFR 21.17. Due to the uniqueness of this equipment, corresponding Operational characteristics, and need for recurring maintenance activity, all ejection seat training, maintenance, and component replacement schedules must be conducted in accordance with the FAA approved Airworthiness Limitations Section of Maintenance Manual P/N 133-590003-7. UPDATE 26 February 2016: In an unrelated development the US Federal Aviation Administration (FAA) has issued an Advisory Circular (AC91-87) titled: Ejection Seat Training Program on how to develop suitable training. UPDATE 24 July 2016: It is now 70 years since the first live in-flight ejection with an MB seat. UPDATE 1 August 2016: TRU Simulation + Training announces they are to provide EASA standard maintenance training courseware for Affinity for the T-6C: The courseware includes development of...
read moreAirbag Explosions: Independent Takata Corp QA Panel (‘Skinner Panel’) Reports
Airbag Explosions: Independent Takata Corp Quality Assurance Panel (‘Skinner Panel’) Reports The deaths of 10 people and 139 injuries worldwide have been linked to defects in motor vehicle airbag inflators made by Japanese supplier Takata Corporation, one of the world’s largest manufacturers of vehicle safety devices. The inflators disintegrated, sending high energy debris towards the vehicle occupants. The first known incident occurred in 2003 in Switzerland. Since 2008, more than 40 million vehicles have been recalled worldwide for maintenance action (half in the US). The US National Highway Traffic Safety Administration (NHTSA) only opened an investigation in 2014, ten years after the first explosion in the US. There was strong criticism of their vigilance (which we discussed at the time: US Vehicle Regulator in Firing Line). They then rapidly imposed a $200 million civil penalty, the largest in their history, on Takata for violations of the National Traffic and Motor Vehicle Safety Act. Later NHTSA fined Takata further for not cooperating. More recalls have been initiated in the last few day by Daimler and VW. A good summary of the saga can be found here: Massive Takata Airbag Recall: Everything You Need to Know The Skinner Panel In late 2014, to supplement other investigations into these occurrences, Takata commissioned the Independent Takata Corporation Quality Assurance Panel to “conduct an unbiased review of Takata’s quality-related practices”. The review was billed as being forward looking, not a response to the past incidents. The Panel was chaired by former US Transportation Secretary Samuel Skinner, who appointed 6 other distinguished panel members (all American) in January 2015. This follows past precedents such as the Baker Panel after the 2005 BP Texas City Explosion, the Toyota North American Quality Advisory Panel, led by another former US Transportation Secretary Rodney Slater which reported in 2011 on a series of unintended acceleration accidents and the 2014 Valukas report for General Motors (which we covered in GM Ignition Switch Debacle – Safety Lessons). The Panel’s mission was also very US centric, concentrating on the airbag-inflator operations of TK Holdings Inc, Takata’s North American subsidiary, to: …review and assess Takata’s current policies, practices, procedures, structure and personnel to ensure that, going forward, Takata is fully and promptly responsive to the traveling public, the US Department of Transportation, the National Highway Traffic Safety Administration, other regulators, and the OEMs— whenever questions are raised about the quality or safety of Takata air bags. QA Review Panel Conclusions The Panel published its report on 2 February 2016 and has concluded that: …Takata must make significant improvements across the quality spectrum and, in particular, in three broad areas: (1) addressing quality-related concerns; (2) ensuring quality in Takata’s design and manufacturing processes; and (3) promoting quality through improved management practices. Recommendations The panel recommended the following in each area (with our comments and selective quotes are in italics): (1) Addressing Quality-Related Concerns Refine the approach to monitoring in-fleet product performance: Currently some tasks are split between a safety team and a warranty team with no data trending. It is suggested Takata buy older cars that are to be scrapped to examine the airbags. Ensure quality and safety concerns can stop product development: While they can stop production they cannot veto design reviews currently. The Panel also say: “Takata should strive to have only the best and brightest on its quality teams”. Ensure that data from quality performance testing is recorded and reported accurately: It seems there has been testing recording and reporting ‘inaccuracies’ in the past. The Panel do not elaborate but allegations have been made in the press:...
read moreFuel Exhaustion Causes EMB-110 Emergency Landing
Fuel Exhaustion Causes EMB-110 Emergency Landing (Wiggins EMB-110 N116WA) The US National Transportation Safety Board (NTSB) has recently reported on a serious incident that involved Embraer EMB-110P1 Bandeirante, N116WA, operated by Wiggins Airways on a cargo flight on 21 May 2014 from Manchester International Airport, NH to Burlington International Airport, VT. The Incident Flight While in cruise at 8,000 ft the fuel low pressure light-boost pump fail light illuminated. Shortly after, the right engine flamed-out first, followed by the left. The pilot declared an emergency and noticed the small Warren-Sugarbush general aviation airfield (with a 2575 feet x 30 feet runway) about 5 miles away. The NSTB say: Immediately upon touchdown he utilized “aggressive braking” and the left tire deflated, the airplane veered to the left, the left main landing gear departed the paved portion of the runway, and subsequently the right tire deflated. …skid marks began about 475 feet after the runway threshold, the left main landing gear departed the paved portion of the runway 942 feet past the initial tire skid marks, and the airplane came to rest 1,509 feet past the initial tire skid marks, with 590 feet of runway remaining. The single pilot was uninjured and the aircraft sustained only minor damage to the left wing flap. The Investigation The NTSB say: Examination of the fuel tanks utilizing both the airplane’s fuel gauges in the cockpit and the dripless stick method revealed that both fuel tanks were devoid of fuel. There was no evidence noted of any fuel leak or staining and the fuel caps were secure and in place. …following the incident maintenance personnel performed a fuel quantity accuracy test and no abnormalities or malfunctions were noted with the fuel quantity indication system. In a statement to an inspector of Vermont Aeronautics the pilot said he: …was called in as a back-up pilot to fly the UPS cargo run from MHT to BTV as the regular pilot called in sick. The pilot explained: …the “normal procedure” for refueling was that the pilot leaves a fuel order the night prior and that 1,000 pounds per side was “their standard fuel load for this run.” He had not observed the fuel upload. He said that he turned on the master switch and that normally the fuel gauges would travel through their full range of indication and then settles back to the amount that the aircraft onboard the aircraft. He stated that he saw 1,000 lbs a side this morning in his check. He stated that he did not observe the gauges cycle through their range of indication, that he was doing other flight deck checks. The NTSB go on: According to a Federal Aviation Administration (FAA) inspector, the airplane was last fueled on May 13, 2014. Since that refueling, the airplane had flown 1.9 flight hours and consumed about 1,200 pounds of fuel. Also during the time from the last refueling and the incident, maintenance personnel performed multiple engine performance runs and two taxi repositions. One maintenance technician reported to the FAA inspector that during an engine run on May 17, 2014, he noted approximately 500 pounds of total fuel on board. No refueling records were located after the May 13, 2014 refueling and before the incident flight. The NTSB therefore concluded that the aircraft had not been refuelled, and the pilot had mistaken in believing there were 2,000 pounds of fuel aboard....
read moreUS HEMS Accident Rates 2006-2015
US HEMS Accident Rates 2006-2015 The safety of US Helicopter Emergency Medical Service (HEMS) operations has been a topic we have discussed previously. With HeliExpo approaching, when 10 years of the International Helicopter Safety Team (IHST) will be marked and with US NTSB Board Member Robert Sumwalt just publishing a HEMS article in Professional Pilot, we thought we’d take a look at how the US HEMS accident rates have changed over the last decade. US HEMS Accident Data Sumwalt helpfully tabulates ten years of accidents (reproduced at the bottom of this page). With 90 deaths and 93 helicopters lost in 92 accidents (one was a mid air collision), Sumwalt notes there has been an accident every 40 days on average. We have converted that into a graph and added 3 year moving averages to better examine the trends (unfortunately HEMS flying hours data is not readily available to refine the data). US HEMS Safety Analysis Accidents: The 3 year moving average has dropped 33% from 12 to 8 per annum, though it seems to have plateaued over the last 5 years. In 2015 there were 7 accidents (22% less than the 10 year average). Fatal Accidents: The 3 year moving average finishes as it started at 4, though the 3 year moving average peaked in 2011 at 7 (due to 12 fatal accidents in 2010). There has been negligible change in the last 4 years. In 2015 there were 5 fatal accidents (14% more than the 10 year average). Fatalities: The 3 year moving average has dropped 33% from 13 to 9 per annum, though it seems to have plateaued over the last 5 years. In 2015 there were 9 fatalities (identical to the 10 year average). US HEMS Accident Trend – Where Next? As Sumwalt highlights, new long awaited Federal Aviation Administration (FAA) regulation changes are coming into effect. On 20 February 2014, the FAA) issued an extensive package of changes to Parts 91, 120 and 135 (following the spike in fatal accidents and fatalities in 2013). This followed proposals in late 2010 (6 years after a specific FAA Task Force was originally created) and the year after the NTSB held a 2009 public hearing on HEMS (triggered by the 20 fatalities in 2008) and issued a series of safety recommendations. But will they spark a noticeable downward trend? Well, maybe. Some of the safety benefit should have already been gained by the enthusiastic early adopters, so the improvement from late, unenthusiastic operators is unlikely to be huge. A recent voluntary industry commitment to Crash Resistant Fuel Systems (CFRS) on older aircraft without the benefit of a CRFS should have an effect on fatalities and on the stubborn fatal accidents rate per annum. However that benefit is by is very nature balanced by the continued operation of aircraft certified in the early 1990s or earlier. Any wider adoption of the various safety initiatives that Sumwalt mentions, including wider implementation and maturity of Safety Management Systems, plus more capable, modern aircraft should also have a positive effect but only time will tell if the industry acts in a concerted way. UPDATE 24 December 2016: Dr Ira Blumen, program/medical director for the University of Chicago’s Aeromedical Network (UCAN) has been tracking US HEMS safety performance since 2000. A recent report based on his data noted: In 1980, a HEMS crewmember had a 1 in 50 chance of being in a fatal accident; today that number is 1:850. From 1972 to 2016...
read moreCulpable Culture of Compliance?
Culpable Culture of Compliance? The Australian Transport Safety Bureau (ATSB) has published their report into a fatal man over board (MOB) from the bulk carrier Cape Splendor off Point Headland, WA on 6 October 2014. This report is of wider interest because it discusses how blindly emphasising compliance without considering risk may create a culture that actually undermines safety. The Fatal Accident The Singaporean flagged 206,000 dwt vessel was anchored 13 miles offshore, awaiting to load iron ore. The bosun descended the accommodation ladder during his lunch break, intending to fish. He lost his balance and fell into the sea. A seaman with him threw a lifebuoy toward the bosun and raised the alarm. The ship’s crew deployed its rescue boat within 10 minutes, and an extensive air and sea search continued for 3 days. However, the bosun was not found. …the bosun and the seaman were not wearing any flotation devices [although they had been when they rigged the ladder before lunch] or fall prevention equipment. The bosun had seen fish below the accommodation ladder that was in the shade, and he probably saw it as a good opportunity to fish without considering the risks involved. The lack of a lifejacket, wet clothing, and possible entanglement with fishing gear, sea conditions, and the current would have adversely affected the bosun’s ability to stay afloat and swim. The ATSB investigation also identified that the ship’s safety management system procedures for working over the ship’s side were not effectively implemented. Hence, the ship’s crew routinely did not take all the required safety precautions when working over the side. Culture The ATSB go on to discuss the culture aboard the ship. Based in interviews and observations they say (emphasis added): Crewmembers did not always consider all possible risks when following safety procedures for work tasks, and they did not see that similar safety precautions were necessary for recreational tasks. On board Cape Splendor, a culture of safety compliance prevailed, wherein people behaved in a safe manner not because they perceived safety as an important organisational goal, but because there was a rule that they felt obliged to obey. Further, this was limited to work tasks, with no evident regard to safety during recreational activity outside of work hours. A genuine commitment to a safety culture had not yet been fully developed. The above demonstrates the challenges faced in striving to ensure that safety values and attitudes are considered across all shipboard activities… Research has shown that employees will take their cues about the importance of safety behaviours from what they observe is rewarded by their supervisors and close superiors, rather than from the company’s policies. It is therefore critically important that masters, officers and supervisors take every opportunity to encourage and reinforce the primary importance of safety at all times, and across all activities. The safety culture on board Cape Splendor was not well developed and the ship’s managers [U-Ming Marine Transport] had earlier identified it as such. A consequence of this inadequacy was the ineffective implementation of working over the side procedures, including the general belief by its crew that safe work practices applied only when working, and not during recreational activities. Our Observations We think that the ATSB neatly reiterates that leadership is a powerful influence on organisational culture, local norms and work practices. While top management can and should have a big influence, its essential to ensure that consistent values, expectations and behaviours...
read moreMachining Defect Cause of V2500 Failure
Machining Defect Cause of V2500 Failure On 18 September 2014 JetBlue Airways Airbus A320-232 N656JB experienced a Number 2 IAE V2527-A5 engine failure and under-cowl fire during initial climb out from Long Beach, California. The US National Transportation Safety Board (NTSB) say in their report: The flightcrew shutdown the No. 2 engine, discharged both fire bottles, and performed an air turnback to Long Beach. The airplane made a successful and uneventful single-engine landing… Examination of the outside of the engine revealed a fractured fuel pressure line…and evidence of thermal distress such as consumed, partially-consumed or oxidized insulation blankets, loop clamps cushions, wiring harness sheathing, and sooting of various components and cases. The investigation concluded the fuel pipe had failed due to excessive vibration. A full engine strip was necessary to identify the cause. …a single fir tree blade retaining lug from the high pressure turbine stage 2 disk had fractured and 2 HPT stage 2 blades had released. Metallurgical examination…revealed evidence of fatigue from multiple origins that propagated from the pressure side (PS) of the middle (No. 2) fillet towards the suction side (SS) almost through the entire width of the lug before finally fracturing due to progressive tensile overload. Closer examination of the fractured lug revealed a concave ‘divot’ in the PS No. 2 fillet, immediately adjacent to the fracture surface. The depth of the ‘divot’ measured up to 0.0008 inches at the fracture origin site and the ‘divot’ was confirmed to run the entire length of the fillet. Visual examination of all the other remaining lugs revealed that same ‘divot’ on PS No. 2 fillet and based on this IAE concluded that the groove appeared to be a tool mark resulting from the original machining (broach) operation. The broaching tool is used to finish 3 discs, each with 72 slots, before re-sharpening (or ‘re-dressing’). The disc of the failed engine was the middle of three discs broached before the next re-sharpening. The other two discs were examined by IAE in March 2015. The first disc had 52 satisfactory slots but the last 20 exhibited the same ‘divot’ tool marks as found on the failed disc. All 72 slots on the third disc has tool marks. In June 2015 IAE then went on to examine the first disc broached after the tool was next sharpened. All 72 slots exhibited the same tool marks as seen previously. Further unique tool marks were found on the PS No. 3 fillet. The NTSB say: Reconditioning of the broaching tool did not correct the ‘divot’ problem, so an audit team made up of IAE, Avio Aero (performed the finished machining/broaching operation), and General Electric (owner of Avio Aero) evaluated the entire manufacturing process with an emphasis on the broaching operation. The evaluation of the Avio disk machining process revealed the following primary contributing factors: 1) cutter tool draft angle design leading to scuffing/sliding along the relief surfaces with associated side loading/deflection and rapid tool wear, 2) a non-optimized tool redressing process resulting in uneven material removal and non-uniform cutter tool profiles, and 3) procedural issues with inspection of tooling, set-up and final parts. Based on these findings, the best practices from GE and IAE have been implemented to address these manufacturing deficiencies. Additionally: …IAE proposed a fleet management plan that would include the issuance of a Non-Modification Service Bulletin (NMSB), anticipated...
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