EASA 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...
read moreIgnoring Corrosive Environment Brings Down B206 Helicopter
Ignoring Corrosive Environment Brings Down B206 Helicopter An operator that ignored the Rolls-Royce M250-C20 Series Engine Operation and Maintenance Manual classification of their entire island operating location as a “severe corrosion operating environment” and failed to do the associated maintenance requirements suffered the loss of the their Bell 206B3. Emerald Pacific Airlines B206B3 B-31019 was hovering at low altitude jet washing high voltage power line insulators 15nm SW of Taichung Airport, Taiwan when it suffered a loss of engine power and forced landing. The aircraft was substantially damaged and the pilot and spray operator suffered minor injuries. The Aviation Safety Council (ASC) of Taiwan concluded that: The aircraft loss of engine power was determined the separation of the 3rd stage blade of engine compressor. The probable causes of blade separation are: 1) an airfoil fracture initiating in a corrosion pit, which then progressed in high cycle fatigue until the blade separated in overload, or 2） blade tip rub caused by delamination of the case plastic lining due to corrosion underneath the vane outer band. The probable cause of the corrosion of the compressor is the improper compressor maintenance during operation in a corrosive environment. The M250-C20 Series engine Operation and Maintenance Manual contains warnings that: salt laden humidity and chemicals will corrode compressor blades and vanes and cause them to fail. Ironically (considering its mission) the operator should have been conducting an after last flight of the day engine wash and also did not follow the engine preservation procedure required when the aircraft had not flown for more than 5 days. The ASC also said: The aircraft operator did not follow the procedures to inspect the erosion and corrosion of the compressor blades and vanes when performing the 300 Hour inspection of compressor. It missed the chance to detect the serious corrosion of the compressor during the last time inspection before occurrence. The ASC also note that the operator did not adjust the default 300 hour periodicity in their Maintenance Programme and had overrun it on at least one occasion. They ASC highlight deficiencies in knowledge of engine maintenance within both the operator and the regulator (the Civil Aeronautics Administration). Other than shortcomings in training they do not analyse the underlying cause of these shortfalls. UPDATE 2 February 2017: TSB Canada release a report on a similar accident. UPDATE 5 February 2017: Our new article Fatal Low Altitude Hover Power Loss: Power Line Maintenance Project looks at how an engine compressor failure while installing power line markers in Canada resulted in that unsurvivable impact and fire. Another Example: Canadian Accident with LTS101 Engine Another example of failure to follow corrosion protection procedures can be found in the Canadian Transportation Safety Board (TSB) report into the loss of Eurocopter AS350B2 C-FLUK on 1 July 2007. Both personnel aboard the helicopter, which was operating in support of seismic survey operations in Saskatchewan, died when the engine suddenly failed while flying over a lake (emphasis added): The helicopter had been modified by a Transport Canada approved Soloy Aviation Ltd. supplementary type certificate (STC) number SR01647SE. The STC authorizes the replacement of the originally supplied TurbomecaArriel engine with a HoneywellLTS-101-700D-2 engine. The engine was a rental engine and had been installed on 17 June 2007. The engine’s number three bearing failed, resulting in a rearward movement of the power turbine shaft which cut the engine’s Py line. As a result, the engine’s rotational speed decreased to about...
read moreUKMFTS Fixed Wing Aircraft Service Provision Contract Awarded
UK Military Flying Training System Fixed Wing (UKMFTS) Aircraft Service Provision Contract Awarded The contract to provide Elementary, Basic and Multi-Engined training aircraft to the UK Military Flying Training System (UKMFTS) through to 2033 has been awarded. The contract was placed by Babcock / Lockheed Martin joint venture Ascent Flight Training. Ascent, selected as the UK MOD’s flying training partner in 2008, will deliver the instruction, infrastructure and support and has awarded the ~£500 million aircraft service provision (ASP) contract to Affinity Flying Training Services, a joint venture of Elbit and KBR. A total of 38 aircraft of three types are involved, with operations commencing between 2018 and 2019 with a mix of civil (Ascent) and military instructors. All feature modern glass cockpits and have been civil certified previously. UKMFTS Elementary Flying Training (EFT) – Grob 120TP ‘Prefect’ Twenty three Grob 120TP aircraft will be used for EFT. While made by Grob, the G120TP (discussed in this 2011 Flight International test pilot review by the late Pete Collins) is a retractable landing gear turboprop trainer that is substantially more advanced that the current Grob 115E Tutor. We discussed the certification of the glass cockpit G120TP in 2014. They are to be designated the Prefect TMk1 in UK military service. They will carry military serials ZM300 to ZM322. The first will be Manufacturer’s Serial Number (MSN) 11099. UPDATE 25 May 2016: The first two of six G120TPs have been delivered to CAE for their contract to train US Army Beechcraft C-12 pilots at Dothan Regional Airport, Alabama. One reason for their selection is they can conduct upset prevention training (the former contract, held by Flight Safety Inc, used a mix of non-aerobatic Cessna 182s supplemented by aerobatic Zlin 242L Gurus) rior to the transition to glass-cockpit C-12s. UPDATE 28 June 2016: See also this article by Dave Unwin: Flight Test: Grob G120TP – The twenty first century trainer UPDATE 19 July 2016: It is reported that the Grob production line is producing 36 G120TPs per annum, with an order backlog to the end of 2018. However, Grob say the tooling is in place to double the rate if extra staff are recruited. The first two examples for UKMFTS are in production and due for delivery in September/October 2016. UPDATE 19 September 2016: Grob / Affinity release photos of G120TPs in UK military colours: UPDATE 17 November 2016: The first Prefects, now on the UK civil register, but later to move to the military register have arrived at RAF Cranwell. UPDATE 18 November 2016: “We are delighted to have delivered these aircraft only 9 months after contract award said Andrew Barrie, Head of KBR’s UK Government Services business (part owner of Affinity). “We are proud to be a part of this significant project and look forward to seeing more aircraft coming on stream next year.” G-MFTS and G-MEFT went on to the UK civil register on 10 November 2016. UPDATE 7 March 2017: Having accepted a 3rd Grob 120TP Prefect in March, the 4th and 5th were delivered to Affinity at RAF Cranwell today. UPDATE 29 June 2017: Seven Grob 120TP Prefects have now been delivered according to Ascent. UPDATE 17 July 2017: The Grob 120TP Prefect T Mk 1 has received is military Release to Service (RTS). UPDATE 1 August 2017: At 10:18 the first training flight with a UKMFTS G120TP, ZM300, took place at RAF Barkston Heath in Lincolnshire, piloted by Squadron Leader Balshaw of...
read moreLeonardo Strives For Greater Gearbox Loss of Lube Capability
Finmeccanica Strives For Greater Gearbox Loss of Lube Capability Finmeccanica Helicopters (the recently rebranded AgustaWestland (UPDATE: and now Leonardo) is working to enhance the durability of helicopter Main Gear Boxes (MGBs) after a loss of lubrication. The company’s Marco Tamborini presented their approach at the European Aviation Safety Agency (EASA) 9th Rotorcraft Symposium held in Cologne in December 2015. His presentation can be downloaded as part of a large zip file from the EASA website or here. Background – Certification & Controversy Often erroneously referred to as a ‘run-dry test’, an ‘Additional Test’, defined in 29.927(c), is required for Category A rotorcraft to demonstrate at least 30 minutes of operation after a loss of MGB lubrication (at least 29 minutes 35 seconds at the minimum torque necessary for sustained flight and then 25 second period to simulate the landing). In a certification memo issued in 2013, EASA say (emphasis added): The intent of the rule change for Category A rotorcraft was to assure that these rotorcraft have significant continued flight capability after the loss of lubricant to any single transmission in order to optimize eventual landing opportunities. Extending the bench testing beyond 30 minutes, although not required, is considered highly desirable. Accomplishing this would further improve the capability of the rotorcraft to reach a suitable landing location in order to improve occupant safety when operating in remote geographic areas that include harsh environmental conditions. The earlier certification of the Sikorsky S-92A MGB was controversial. As we have reported, the Norwegian Accident Investigation Board (AIBN) has recently commented: In 2002, Sikorsky carried out a test of the main gear box, where the oil was drained… A catastrophic failure occurred after 11 minutes. Accordingly, the requirement for 30 minutes’ safe operation was not met. With reference to AC 29-2C, Sikorsky decided to install a bypass valve in the external oil cooler circuit. By closing the valve, any external oil leaks could be stopped. It was considered extremely remote that other leaks in the oil system could prevent a safe landing within 30 minutes. This was accepted by the certification authority, the Federal Aviation Administration (FAA). Sikorsky was the only manufacturer to seek such an alleviation. In service two leaks occurred outside of the S-92A oil cooler, destroying the myth that such failures were extremely remote. Tragically the second resulted in the S-92A fatal accident offshore Canada in 2009 in which 17 people died, although miraculously one passenger survived. This has triggered both further work on helicopter ditching and on transmission loss of lubrication rule making. See also: Helicopter MGB oil system failure analysis using influence diagrams and random failure probabilities The Finmeccanica MGB Loss of Lubrication Strategy Finmeccanica has a 5 stage design strategy: Minimising the probability of a major oil loss (e.g replacing external pipe work with cast internal passages, having redundant pumps, fail-safe fittings, not sharing lubrication with external accessories and enhanced pre-delivery checks) Minimising power losses to reduce heat build up (e.g minimising the number of reduction stages, using fine pitch gears to reduce sliding velocity and super-finishing, adding shrouds to reduce windage drag, preferring roller bearings, ceramic elements and low friction coatings). At minimum cruise power the AW189 MGB efficiency is 96.5%. Maximising heat rejection (e.g improving MGB bay ventilation to help if flow through the oil cooler stops) Increasing high temperature running capability (e.g. maintaining clearances, plays and backlashes even at the highest expected temperatures, using High Hot Hardness (H3) steel for gears and bearings and heat tolerant silver-plated bearing cages)...
read moreSafety Lessons from TransAsia ATR-72 Flight GE222 CFIT
Safety Lessons from TransAsia ATR-72 Flight GE222 CFIT The Aviation Safety Council (ASC) of Taiwan has issued their investigation report into the loss of TransAsia Airways (TNA) ATR 72-500 B-22810 on 23 July 2014 during an attempted landing in poor weather. It highlights a number of important safety lessons. The Accident During a non-precision approach, after around 34 minutes of holding, the aircraft impacted terrain in a residential area 800m NE of the threshold of runway 20 at Magong Airport, Penghu Islands, Taiwan during a heavy thunderstorm associated with Typhoon Matmo. Ten of the 58 on board survived. The Commander was Pilot Flying (age 60, ex-military, joined airline in 1992, ATPL, 22,994 hours total, 19,070 hours on ATR42/72) and the First Officer (FO) was Pilot Monitoring (age 39, direct recruit by the airline in 2011, CPL, 2,393 hours total, 2,084 hours on ATR42/72). There was no approach briefing before commencing descent and the FO “proposed that he conducted the before landing check by himself without a cross-check”, which the Commander approved. The ASC say the Controlled Flight Into Terrain (CFIT) occurred because: The crew continued the approach below the [330ft] minimum descent altitude (MDA) when they were not visual with the runway environment contrary to standard operating procedures. When the aircraft had descended to 249 feet, the first officer illustrated the position of the [Missed Approach Point] MAPt by saying “we will get to zero point two miles”. At 1905:44, altitude 219 feet, the captain disengaged the autopilot. Four seconds later, the captain announced “maintain two hundred”. The captain maintained the aircraft’s altitude between approximately 168 and 192 feet in the following 10 seconds… The flight crew intentionally operated the aircraft below the MDA…while attempting to visually sight the runway so they could land the aircraft. Neither flight crew member recognised the need for a missed approach until the aircraft was at just 72ft, 0.5 nm beyond the MAPt, where impact with the terrain was “unavoidable”. Further accident site photos can be found here and here. During the investigation the ASC used an unmanned air vehicle (UAV aka RPAS aka drone) to assist with the site survey. Having discussed the effect of a cockpit gradient, the ASC note that in interviews with other TransAsia crews the consensus was that “the occurrence first officer would accommodate the captains’ flying habits, and tended not to challenge captains’ landing decisions”. We have previously discussed whether it is better for the Commander to be the Pilot Flying or the Pilot Monitoring and this accident re-emphasises that question. However, we do note below that the FO did intervene after several course, mode and communication errors by the Commander. Should We Just Blame the Pilots or Look Deeper? As is perhaps inevitable, the press simplistically ‘blamed’ ‘pilot error’. Reminiscent of two business jet accidents we have previously discussed in the US and France), the ASC say: According to the flight recorders data, non-compliance with standard operating procedures (SOPs) was a repeated practice during the occurrence flight. The ASC also say the Commander was “likely overconfident in his flying skills”, potential the reason for pressing on below MDA. We do note however a Uni Air ATR72-600 aircraft had successfully landed on Runway 20 just 8 minutes earlier which may have influenced the Commander’s behaviour. However, it would be no surprise to any aviation safety professional that the ASC report revealed a range of systemic factors. Systemic Factors – Fatigue The ASC used QinetiQ’s System for Aircrew Fatigue Evaluation (SAFE) biomathematical fatigue model in...
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