2009 Newfoundland S-92A C-GZCH Accident: A Failure of Design and Certification
2009 Newfoundland S-92A C-GZCH Accident: A Failure of Design and Certification 12th March marks the anniversary of the 2009 loss of a Sikorsky S-92A off Newfoundland, Canada after two (of three) mounting studs, holding the Main Gear Box (MGB) oil filter failed, allowing a massive MGB oil loss. While 17 people died in that preventable accident, fortuitously one passenger, Robert Decker, survived (video of his eyewitness account). Controversially, following a failure during Sikorsky certification testing in 2002, the US Federal Aviation Administration (FAA) had allowed the certification of the type with a uniquely lax interpretation of the certification requirements for loss of lubrication testing. “Truth in politics is optional – Truth in engineering is mandatory.” Igor Sikorsky (1889-1972) Despite misleading social media statements by the then Sikorsky S-92A Project Director (albeit countered by others as mentioned by the TSB) that the MGB had been tested for 3 hours, with a genuine loss of lubricant the MGB disintegrated in just 11 minutes. A Preventable Accident The Canadian Transportation Safety Board (TSB) reported in 2011 on the accident to Cougar S-92A C-GZCH Flight 491. The TSB said the: …mounting studs had fractured by overstress extension of fatigue cracks. Fretting and rub patterns observed on the filter housing and packing indicated that the fatigue cracking developed in the forward stud, causing it to fail, which increased the load on the aft stud leading to its failure. Such failures of MGB filter mounting studs (or bolts) is not unheard of (in these cases on Australian operated WHL Sea King Mk 50s): Source: SURVEY OF SERIOUS AIRCRAFT ACCIDENTS INVOLVING FATIGUE FRACTURE VOL. 2 ROTARY-WING AIRCRAFT by Glen S. Campbell, R.T.C. Lahey National Aeronautical Establishment (Canada, 1983). TSB state: On 06 August 2002, Sikorsky carried out its initial certification loss of lubricant test by draining the MGB and using only the remaining residual oil (approximately 1.3 gallons) then continuing operation in accordance with the requirements of AC 29-2C. The purpose of this test, outlined in the test documentation, was to demonstrate that the S-92A transmission could provide, “continued safe operation for a minimum of 30 minutes following a complete loss of lubricating oil in accordance with the requirements of FAR 29.927(c)(1).” … Sikorsky and the FAA expected that, based on the similarities between the S-92A’s MGB and the Sikorsky S-60 [sic: H-60 / S-70] Black Hawk‘s MGB, the S-92A’s MGB would successfully operate for 30 minutes after draining the lubricating oil. The FAA indicated that the initial test was thought to be a low risk test, and Sikorsky scheduled it very late in the overall S-92A certification program. This original S-92A test matched the way other manufacturers conducted such a loss of lubrication test. TSB explain that: EASA indicated that applicants in its jurisdiction normally complied with Part 29.927(c)(1) by draining the MGB and continuing operation with only residual oil. Prior to the S-92A certification validation it had already tested and certified at least four helicopters using this criterion. Aerossurance is aware that Canadian manufacturers also followed the same interpretation as the European manufacturers. Unfortunately with just 1.3 gallons of oil the S-92A MGB: …suffered a catastrophic failure about 11 minutes after the test was started. TSB go on: Following the loss of lubricant test resulting in catastrophic failure, instead of taking steps to redesign the transmission to provide a 30 minute run dry capability [sic: this term is not used in regulation] for the MGB, Sikorsky re-visited the requirements...
read moreStep Change in Safety: Helicopter Safety Update 2016
Step Change in Safety: Helicopter Safety Update 2016 Step Change in Safety held a webinar on North Sea helicopter safety (covering CA-EBS, emergency egress, FCOMs and airworthiness matters) on 9 March 2016 (following on from a March 2015 event we have previously covered). Introduction Step Change is a tripartite UK offshore health and safety organisation combining companies, unions and regulators, formed in 1997. The organisation has 5 strategic themes, each with a steering group: Asset integrity Competence & human factors Workforce engagement Simplification (and standardisation) Helicopter safety Les Linklater, Executive Director of SCinS, briefed on the activity of the Helicopter Safety Steering Group (the HSSG). In particular he discussed the introduction of Category A Compressed Air- Emergency Breathing Systems (CA-EBS) and passenger size procedures following the UK Civil Aviation Authority (CAA) CAP1145 report published 20 February 2014. Category CA-EBS We have previously discussed at length the rapid development, certification and introduction of the Survitec Mk50 Passenger Lifejacket with a Compressed Air EBS (CA-EBS). The earlier LAPP Jacket with a hybrid rebreather has recently been withdrawn from HUET training with the introduction of a new OPITO Basic Offshore Safety Induction and Emergency Training (BOSIET) and Further Offshore Emergency Training (FOET) standard (which we have previously discussed). The Mk50 lifejacket is now used, however ‘wet’ CA-EBS training has not been introduced as yet. It was noted that the CA-EBS is a “fundamentally better” system than the previous hybrid rebreather and the goal is to introduce wet training. The UK regulator, the Health and Safety Executive (HSE), “perceive a risk” of barotrauma for repeated ascents from a depth of 1.5m during HUET. This was called a “minuscule’ risk but one that that “needs to be managed”. It was suggested during Q&A that it was originally understood that the HSE would waive certain requirements of the Diving at Work Regulations during HUET training but that a “risk averse” position is currently being taken. Engagement on the medical requirements are still on-going. Participants made positive comments about the revised HUET training but there was support for resolving the issues to allow wet training. In the UK the Survitec Mk50 passenger lifejacket and CA-EBS in use. Two performance reviews have been successfully held with Survitec on the Mk50 jacket. Survitec Mk51 and Viking jackets with CA-EBS are to be used for flight crew. CA-EBS implementation is estimated to have cost about £20 million across the UK workforce. Passenger Size Passenger size has also proved an implementation challenge, hence the decision to focus on bi-deltoid shoulder measurement as an appropriate single measurement which can be done by trained offshore medics. Implementing this measurement programme was a ~£1 million investment to measure 75,000 people. Passengers classified as Extra Broad (XBR) have bi-deltoid measurement >22in. XBR passengers must seat in selected, marked seats with escape routes compatible with their size. Over 75,000 UK offshore personnel have been measured, only 3% are XBR and none the Super XBR category. As 30% of seats in the current fleet are XPR compatible (shaded grey in the diagram below) it is unlikely this restriction will every adversely affect any individual flight. It has been decided that only those with an initial measurement of over 20in will be re-measured every 4 years (prior to HUET training and ideally, for simplicity and efficiency, by offshore medics). There had been feedback that the XBR seating is not consistently occurring on return journeys (were Helideck Landing Officers [HLO] are...
read moreShell Pernis 11.2t Ethylene Oxide Leak
Shell Pernis 11.2t Ethylene Oxide Leak The Dutch Safety Board has reported (in Dutch) on the leak of 11.2 tonnes of ethylene oxide from a overhead pipe at the 550 hectare Shell Pernis oil refinery on 30 December 2013. The leak was detected by a site worker at what is Europe’s largest refinery, surrounded by 500,000 inhabitants. Ethylene oxide is toxic, carcinogenic, ignites easily and may explode. The DSB say their investigation shows that Shell was not prepared for such a leak of that size. The adjacent port had to be evacuated due to the level of airborne contamination, and a water curtain used had the side effect of increasing the ground contamination. The spill occurred because the insulated pipework joints has degraded internally over 18 years. The DSB say that Shell had assumed a 40 year design life and that the joints would be maintenance free for 20 years. Following the spill, Shell has taken a series of measures. The joints have been replaced by flanges which can be routinely inspected. Shell now uses technical means to detect leaks in a timely manner and emergency procedures have been revised. Not The Only Leak Shell had suffered leaks of the same chemical in 2007 and 2009. During the completion of this report, the DSB launched an investigation into the emission of another 25 tonnes of ethylene oxide at a sister plant at Shell Moerdijk. It is alleged that this leak, following a repair in November 2015, was only discovered 2.5 months later. We have also previously reported on an earlier explosion there: Shell Moerdijk Explosion: “Failure to Learn” UPDATE 10 August 2016: It is reported that the UK Health and Safety Executive (HSE) have issued an Improvement Notice to Shell in the UK on its Clipper Southern North Sea complex of five bridge linked platforms, after one of their inspectors warned that: …“significant changes” to the Clipper installation meant there was risk of loss of containment from corrosion under insulation (CUI). In one instance, a four inch condensate line had to be shut down after it was discovered the thickness of the wall was just 2.6mm – a significant decrease on its nominal measurement of 11.1mm. A notice from the HSE also said “certain hydrocarbon containing lines” were three years behind their planned inspection date while certain lines had not been inspected for more than 12 years. But further: It was also found Shell had reduced its CUI inspection and repair programme staffing in March from 24 persons to eight people, which reduced the “ability to execute inspection and repairs in a timely manner”. In the 2008 book Resilience Engineering Perspectives, Volume 1: Remaining Sensitive to the Possibility of Failure, John Wetherall writes: …one hallmark of a resilient organisation is that it is prepared not only for its own failures those of which it can learn from others – the more resilient it is, the ‘bigger’ are the lessons it has learnt from others. Aerossurance has extensive safety and accident analysis experience. For aviation advice you can trust, contact us at: enquiries@aerossurance.com Follow us on LinkedIn and on Twitter @Aerossurance for our latest updates. TRANSLATE with x English Arabic Hebrew Polish Bulgarian Hindi Portuguese Catalan Hmong Daw Romanian Chinese Simplified Hungarian Russian Chinese Traditional Indonesian Slovak Czech Italian Slovenian Danish Japanese Spanish Dutch Klingon Swedish English Korean Thai Estonian Latvian Turkish Finnish Lithuanian Ukrainian French Malay Urdu German Maltese Vietnamese Greek...
read moreForgotten Fasteners – Serious Incidents
Forgotten Fasteners – Serious Incidents We examine three incidents where fasteners were forgotten during maintenance. It two cases these maintenance errors resulted in parts falling from the aircraft. In a third, a massive fuel leak occurred. Incident 1 – Twin Otter Mission Pod The Irish Air Accident Investigation Unit (AAIU) has recently reported on a serious incident that occurred on 15 August 2015 involving DHC-6-300 Twin Otter C-GSGF, used for aerial survey work by Sander Geophysics Ltd (SGL). Incident 1 – The Flight The aircraft was in Ireland for the low-level Tellus survey project of the Geological Survey of Ireland: The aircraft is equipped with three geophysical instruments which measure the magnetism, radioactivity and conductivity of the Earth below. It undertakes measurements as it flies at a speed of approximately 130 mph (approx 216km/h). The aircraft flies at 60 m (196 ft) above ground level… Survey lines are flown at a spacing of 200 m. The AAIU say: On take-off from Weston Airport, County Kildare the nose cone from the right hand mission equipment pod fell from the aircraft… The Flight Crew experienced a significant amount of yaw to the right which they felt through the flying controls. The aircraft diverted to Dublin Airport where it subsequently landed safely. There were no injuries. One of the three sensors in use was an Electro Magnetic (EM) system. A signal is transmitted from the right hand wing tip pod and the signal is received in the left pod. Incident 1 – The Safety Investigation The AAIU say: On 14 August 2015, the day before the event, in accordance with the maintenance instructions prescribed in the [mission modification’s Supplemental Type Certificate] STC, the aircraft underwent a 125 hour Supplementary Inspection. This inspection called, inter alia, for the removal of “the EM pod nose and tail cones” and inspection of “the pod internal frames for cracks or other damage”. …the Operator’s standard practice calls for the fitting of flagging tape when parts are removed and that the flagging tape should only be removed following re-installation of the removed part(s). On this occasion the personnel involved advised the Investigation that flagging tape was not fitted. It was reported that during the EM Pod maintenance, while the nose cone was being reinstalled, a fault was detected with its sensor system. Re-installation of the nose cone was halted pending identification of the cause of the fault and consequently only the top two nose cone retaining screws were re-installed. Troubleshooting subsequently traced the origin of the sensor problem to a location inboard of the pod and the fault was rectified. The Inspection was then completed but the 14 remaining nose cone retaining screws were not re-installed. The AAIU say: All personnel who completed walkaround inspections on the morning of the event had completed a third party, computer based Aviation Maintenance Human Factors course… There is no mention of the use of more interactive or tailored training. The check was recorded in the Tech Log but it would not necessarily have been apparent that the nose cone had been removed to the crew. The Flight Manual Supplement does have a requirement to “check that all visible attaching fasteners are installed and secure”. The Commander said that he “…there’s not any moving parts on the pods. I had a cursory look at the pods probably from about fifteen feet ahead...
read moreHeli-Expo 2016 Photo Report
Heli-Expo 2016 Photo Report News from HAI Heli-Expo 2016 in Louisville, Kentucky (1-3 March 2016): Airbus Helicopters H215 Airbus Helicopters had on show the newly designated H215, formerly the AS332C1e (i.e. an enhanced, short fuselage Super Puma) and AS332L1e (the long fuselage version), to be built in Romania and aimed at aerial work, disaster relief and other missions. The replacement of elderly SA330Js, S-61s and Mil Mi-8s being distinct targets. The Finnish Border Guard recently took delivery of its first H215, OH-HVP, with the second to follow in Apri 2016l. It has been suggested that a major current sales target is California’s Department of Forestry and Fire Protection (CAL FIRE), which has issued a tender for 15 helicopters. Airbus Helicopters AS350 / H125 Probably one of the oddest special mission modifications on show was this AS350B3 fitted for environmental research. The so called Helicopter Observation Platform (HOP), N350UM, is owned by the University of Miami Rosenstiel School of Marine and Atmospheric Science and operated by Helicopter Express. The aircraft was exhibited by Donaldson Aerospace & Defense as it is equipped with a Donaldson Inlet Barrier Filtration (IBF) system. Meanwhile Vector Aerospace and Robertson Fuel Systems were exhibiting their soon to be certified (by FAA and EASA) Crash Resistant Fuel System (CRFS) for the AS350 AStar and EC130B4. This direct replacement tank features a number of safety enhancements, including the introduction of modern fuel retention technology and the relocation of certain critical components to further enhance safety and ease of maintenance. Vector worked closely with Onboard Systems to ensure that the tank remained compatible with Onboard’s cargo swing options. For more on the value of this modification see our article: Crashworthiness and a Fiery Frisco US HEMS Accident Airbus Helicopters H130 Canadian operator Phoenix Heli-Flight took delivery of a spectacularly painted H130 at the show. Airbus Helicopters H160 and H175 While Airbus did not exhibit aircraft or mock-ups of the H160 and H175 this year they did offer attendees a virtual reality experience with both. Meanwhile it has been reported that Airbus Helicopters are planning a new lean production philosophy for the H160. ‘Major Component Assemblies’ will be produced in different locations before final assembly and flight test at Marignane in France. Production aircraft will have their tail booms produced Albacete, Spain, and main rotor blades would be produced at La Courneuve, near Paris. The central and front fuselages will be produced and pre-equipped by Airbus at its Donauworth facility in southern Germany. They will be mated together in Marignane with the main dynamic components that are also produced there. This could see the 36 week assembly process for the AS365 drop to 18 weeks for the H160, when the production line opens in 2017. UPDATE 10 October 2016: The H160 has now achieved 250 hours in flight test. Bell 505 Jet Ranger X Two Bell B505s were on display. The B505 first flew with a single, right hand side, horizontal stabiliser. The type has now a rather less elegant solution. The Bell 505 features a Garmin G1000H avionic suite. Bell 525 Relentless Bell also brought B525 Flight Test Vehicle 2 (FTV2) to the show. The second aircraft first flew on 21 Dec 2015. The 525 utilises fly-by-wire (FBW) controls. A third aircraft is due to join the flight test programme in the coming month, to be followed by two...
read moreMisrouted Engine Fuel Control Cable Hawker 800XP
Misrouted Engine Fuel Control Cable Hawker 800XP In Issue 4/2015 of TP 6980 – Canadian Aviation Service Difficulty Reports – Feedback an maintenance error involving a Hawker 800XP fuel control cable is reported: During a planned major structural inspection, the technician noticed that the no.1 engine high-pressure fuel lever cable was trapped under the cover of the electrical junction box. The box straddles the area beneath the floor. Luckily the cable was still able to move and function normally as there was only a slight cable deflection under a flexible plastic cover. The cable was inspected, found to be serviceable with no apparent damage. The cable was properly re-routed above the junction box as per the maintenance manual requirements. Transport Canada say: The mis-routing of this control cable was done at either its last replacement or re-installation from a past maintenance check or snag rectification. As it is with any primary flight or engine control, an independent inspection and dual sign-off would have been required as stated in CAR standard 571.10, maintenance release. Transport Canada Civil Aviation would like to advise all maintenance personnel that the inspection criteria includes an operational check and confirmation for correct assembly of the complete affected system. Our readers will know Aerossurance has previously discussed independent inspections several times, including: Critical Maintenance Tasks: EASA Part-M & -145 Change EC130B4 Accident: Incorrect TRDS Bearing Installation You may also find these earlier articles of interest: James Reason’s 12 Principles of Error Management Maintenance Human Factors: The Next Generation Aerossurance worked with the Flight Safety Foundation (FSF) to create a Maintenance Observation Program (MOP) requirement for their contractible BARSOHO offshore helicopter Safety Performance Requirements to help learning about routine maintenance and then to initiate safety improvements: Aerossurance can provide practice guidance and specialist support to successfully implement a MOP. Aerossurance has extensive air safety, airworthiness, human factors and safety analysis experience. For aviation advice you can trust, contact us at: enquiries@aerossurance.com Follow us on LinkedIn and on Twitter @Aerossurance for our latest...
read morePitot Punctures Floats in Icelandic SAR Ditching
Pitot Punctures Floats in Icelandic SAR Ditching The ditching of Icelandic Coast Guard Aérospatiale SA365N Dauphin TF-SIF in the Atlantic off Reykjavik on 16 July 2007 highlights the importance of avoiding protuberances that can puncture emergency flotation systems, careful configuration management and establishing emergency drills. The Icelandic Transportation Safety Board (ITSB), the RNF, issued their report in December 2010. The Accident Flight The aircraft was on a winch training mission to hoist people from the Slysavarnarfélagið Landsbjörg (ICE-SAR) 16m Arun Class lifeboat BS Einar Sigurjónsson, a life raft and from the water at a training area about 8 minutes from their base at Reykjavik’s domestic airport. The RNF say that: …arriving at the training area, the aircraft was flown in a standard pattern at 200 feet and 60 knots IAS and then descended to 100 feet and 20 knots IAS. When the training session began, the aircraft was hovered at 45-50 feet and 0-5 knots GS. At this time a power check was made and the pre-hoist checklist was completed. According to the commander’s statement, all parameters were normal and the torque was approximately 85%. The commander announced to the crew that the aircraft was in Class 3 performance and the aircraft would be ditched in case of an engine or tail rotor failure. The aircraft was operating in a light wind (10 knots) and at ISA-1 (14°C). Being Performance Class 3 (PC3) highlights the risk of conducting live winching on an aircraft with limited One Engine Inoperative (OEI) performance. While in the hover at 45 feet, the crew commenced an operation to winch a rescue litter down to the lifeboat. About 3 seconds after the line was free from the litter the low Nr [main rotor speed] horn started to sound… [and]…the crew noticed a power loss followed by a reduction of Nr. The PF [Pilot Flying] directed the aircraft away from the ship and scanned the caution warning panel for warning lights but saw none lit. The PNF [Pilot Not Flying] looked at the Nr indicator and determined it to show Nr between 300 and 330 (Normal Nr is 355) rpm and the aircraft was losing altitude. About 10 seconds after the horn first sound, the crew deployed the floats and 7 seconds after that made a controlled ditching in water estimated to be Sea State 2-3. …the crew retarded the fuel flow control lever (FFCL) in order to shut off the engines. The pilot reported that when shutting off the right hand engine the engine seemed to be already on low rotation speed. The crew then stopped the main rotor by applying the rotor brake and then cut the hoist wire. After a short briefing the crew shut the battery off as well as the gyros. The crew then evacuated the aircraft through the right hand sliding door and swam to a boat from BS Einar Sigurjónsson. The RNF note the evacuation was a surprisingly unhurried 4 minutes after ditching. The floats had inflated correctly however the crew noticed when they evacuated that that the front floats were rubbing against the pitot tubes and shortly after the forward chamber of the right hand front float deflated. The aircraft capsized approximately 18 minutes after ditching. The Safety Investigation The helicopter was fitted with a Cockpit Voice Recorder (CVR), though not a Flight Data Recorder (FDR). Acoustic analysis of he CVR showed that one...
read moreFalcon 7X LOC-I Due To Solder Defect
Falcon 7X LOC-I Due To Solder Defect On 25 May 2011, Dassault Falcon 7X business jet, HB-JFN, operated by Jet-Link, suffered a pitch trim runaway that caused a 40° pitch up, rapid climb and temporary Loss of Control Inflight (LOC-I) over Malaysia. First flown in 2005 and certified in April 2007, after a 590 flight, 1600 flying hour test programme, the 7X features a fly-by-wire (FBW) control system. This Digital Flight Control System (DFCS) and the Falcon family’s EASY (Enhanced Avionics SYstem) flight deck design draw on Dassault’s 30 years of military fighter experience, especially its Rafale and Mirage 2000. The type had accumulated 75000 flying hours at the time of the incident. The French Bureau d’Enquêtes et d’Analyses (BEA), to whom the investigation was delegated, has now reported (in French) on this serious incident (commenting that the long duration was necessary to examine the organisational factors). The Incident Flight While descending through 13000 feet at the end of a positioning flight to Kuala Lumpur, over 15 seconds the elevator pitch trim began to move from neutral to the full nose-up position. The First Officer (Pilot Flying), a former military pilot with experience on Mirage IV and Mirage 2000, put the aircraft into a steep right-hand bank to aid recovery partially replicating the ‘palier-ressource’ military manoeuvre (which involves approaching a target in level flight before pulling up at 30° pitch to release the weapon, and then banking to 90° to reduce pitch and escape). At two points (for 9 and 12 seconds) both the Commander (Pilot Non-Flying) and the First Officer were simultaneously using their side stick. The First Officer used the priority button to override the Commander’s inputs and asked him to stop. The pitch subsequently decreased, as did the load factor (from a maximum of 4.6 g to less than 1.5 g). After about 2.5 minutes the crew regained control and landed safely. The aircraft had however climbed to 22500 feet. Immediate Response The incident prompted such concern that the next day that the European Aviation Safety Agency (EASA) published an Emergency Airworthiness Directive (EAD), prohibiting further flights by the Falcon 7X fleet until further notice. A further Airworthiness Directive (AD), in two stages, permitted operations to resume with modifications and operational limitations. A third AD with modifications and operational tests followed. The Safety Investigation The BEA found that a defective ‘cold’ solder joint at a pin of a component of the Horizontal Stabilizer Electronic Control Unit (HSECU) led this computer to sending erroneous signal to the actuator driving the horizontal stabiliser trim (HRT) and a simultaneous failures of monitoring channel which were not detected. The solder had not reached an adequate temperature because the board had acted as a heat sink, resulting in micro-cracking. They highlight a similar, but unconnected case in 2007 (Airbus A321 I-BIXK that suffered a braking failure after similar solder defects in its Brakes and Steering Control Unit). A number of contributory factors are identified by the BEA. One is the non-detection of the production fault. They also comment on the HSECU supplier’s Failure Modes and Effects Analysis (FMEA) which was not suitably comprehensive. They note that this FMEA was not subject to detailed review by the aircraft Type Certificate (TC) Holder. The TC Holder’s System Safety Assessment (SSA) in accordance with 25.1309, being partly based on that FMEA, was therefore incomplete. The BEA also reference safety assessment lessons from an Australian Transport Safety Bureau (ATSB) report into an upset involving a A330 VH-QPA in 2008 (in that case not...
read moreUK CAA CAP1145 North Sea Helicopter Safety Two Years On
UK CAA CAP1145 North Sea Helicopter Safety Two Years On Not long after the fatal loss of Eurocopter AS332L2 G-WNSB of Sumburgh Airport, Shetland Islands on 23 August 2013 with 4 fatalities (AAIB Special Bulletin), the UK Civil Aviation Authority (CAA) launched an rapid review on offshore helicopter safety. That CAA Review resulted in the CAP1145 report (‘Safety review of offshore public transport helicopter operations in support of the exploitation of oil and gas’), issued two years ago on 20 February 2014. Last year the CAA issued CAP 1243, the Offshore Helicopter Review Progress Report, which provides an update on the 10 months to 31 Dec 2014. The minutes of the 16 October 2015 meeting of the Offshore Helicopter Safety Action Group (OHSAG) suggest the next CAP1145 progress report is due in April 2016. When they refreshed their website in late 2015 the UK CAA introduced a blog section with the opportunity for public comment and questions. This includes one on offshore helicopter operations, which has had the most interaction to date (on two topics we have previously written about certified sea states limits and CA-EBS training). UPDATE 24 September 2016: The UKCAA has issued CAP1386, their second update on CAP1145. We have summarised that report. UPDATE 1 February 2017: An update of BARSOHO (Version 3), fully aligned with the HeliOffshore SPM, is now available. Aerossurance is pleased to be supporting both HeliOffshore and the Flight Safety Foundation in their work to improve offshore helicopter safety. UPDATE 6 March 2017: HSS3b is issued (initially in Norwegian, with an English Exec Summary). It features comment on CAP 1145 and survivability matters. UPDATE 23 January 2020: Without fanfare UK CAA publish CAP 1877: Safety Review of Offshore Public Transport Helicopter Operations in Support of the Exploitation of Oil and Gas Aerossurance is an Aberdeen based aviation consultancy. For expert advice you can trust on offshore helicopter safety, survivability, safety assurance, safety culture and contracting matters, contact us at enquiries@aerossurance.com Follow us on LinkedIn and on Twitter @Aerossurance for our latest...
read moreUS Helicopter Accident Rate Analysis
US Helicopter Accident Rate Analysis Aerossurance recently looked at US Helicopter Emergency Medical Service (HEMS) accident data for the last 10 years and has also examined accident rates in Gulf of Mexico (GOM) oil and gas operations. We thought we would also look at published accident rates for all US helicopters and demonstrate the effects of choosing different start dates and different trending methods. To look, initially, at performance during the 21st century we choose to use data from the International Helicopter Safety Team’s (IHST‘s) US regional team, the US Helicopter Safety Team (USHST). This is topical as this data has recently been discussed in a magazine article: What We Don’t Know Has Hurt Us. We then take a take a longer historic perspective back to 1970. US Helicopter Fatal Accident Rates 2001-2015 In October 2015 the USHST published data for 2001-2015 (with the latter being a part year estimate) for fatal helicopter accidents per 100,000 flying hours. We’ve plotted this data (excluded the partial 2015 results) and added a linear trend line (i.e. a best-fit straight line): This shows an impressive improvement over the period. But what if we apply a rolling (or moving) average? A rolling average smoothes fluctuations to show a pattern or trend more clearly. If we choose a three year rolling average (i.e. we plot data based on the average of the last 3 years) then the results look very different: Here the poor start to the data set in 2001-2003 dominates the early rolling averages but in more recent years the data, while fluctuating, has essentially plateaued. Similar results are evident in 2 or 5 year rolling averages are selected. If we were to choose a different start point, say 2006, the first year after the IHST was created, and revert to a linear trendline the results are even more dramatic: Almost no change in fatal accident rate over 9 years is evident. If we use a 3 year rolling average: Here the rolling average has risen in recent years, very different to the liner trend. US Helicopter Accident Rates 2001-2015 In October 2015 the USHST also published data for 2001-2015 for helicopter accidents (fatal and non-fatal) per 100,ooo flying hours. Unfortunately 2001-2005 is presented only as an average: You will note that the USHST compare 2015 performance with the baseline 5 year average for 2001-20o5 (a 55% improvement). The 2015 data is however only 20% better than 2006. We can plot average data for 2001-2005 and annual data for 2006-2014 (again ignoring the partial data for 2015) with a linear trend: This shows a dramatic (over 50%) improvement. However, if we use a 3 year rolling average: Here, although the trend reduces during the middle part of the last decade, in recent years the rate has again essentially plateaued. If we focus just on 2006 onwards and apply a linear trend: A modest improvement is evident over the period. If we apply a 3 year rolling average: Very little improvement is now evident. US Helicopter Accident Rates 1970-2013 To take a more historic perspective we have take data from the Helicopter Association International (HAI). There website contains data from 2001 to 2013 (we have taken the most recent record for each year to allow for any revisions as any new, mostly usage data, has emerged). In the Aerossurance achieves we have HAI published data back to 1970. This data is generally...
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