HeliOffshore HUMS Best Practice Guide Wins Safety Award
HeliOffshore HUMS Best Practice Guide Wins Safety Award Against stiff competition the HeliOffshore team who produced a Health & Usage Monitoring System (HUMS) Best Practice Guide have won the Award for Sharing and Learning at the Offshore Safety Awards 2016. That award, sponsored by Centrica: …recognises an individual/team or company that can demonstrate a learning and sharing culture either within their organisation, or who has made a significant contribution to health and safety through active participation in, or engagement with Oil & Gas UK or Step Change in Safety. The offshore helicopter safety organisation launched their HUMS Best Practice Guide in November 2015 to standardise and improve HUMS use worldwide. The award organisers noted that the launch of the 41 page HUMS Best Practice Guide and the shorter Implementation Guide, are: …the result of a highly engaged industry putting momentum behind actions that will make the greatest difference to safety and of the collaborative and global approach taken by the HUMS working group. The team was lead by Russell Gould (Director, Global Fleet Support, Bristow Group) and Malcolm Garrington (Manager HUMS Support, CHC) who collected the prize. Video. After the Awards, Alexander Burnett MSP, Shadow Energy Spokesman, lodged a motion in the Scottish Parliament congratulating everyone who took part in the Awards and welcoming “all of the people and businesses that are helping make a positive difference to safety in the North Sea.” The guides were the result of more than 12 months of hard work and over twenty meetings between the HUMS specialists from CHC, Babcock, ERA, Bristow, PHI, Weststar, Cougar and Bell. They have been made freely available to all helicopter operators, irrespective of whether they are members of HeliOffshore. UPDATE 24 September 2016: In CAP1386, the UK CAA’s second update to their CAP1145 report (discussed further here), the CAA state that they have (emphasis added): …reviewed CAA guidance material (CAP 753) and have made amendments [note: yet to be published] to reflect the EASA Certification Memorandum CM-DASA-001, which clarifies the terminology and the alert generation systems to ensure consistency. HeliOffshore… has produced a HUMS Best Practice Guide which draws upon the in-service experience of a number of experts and Helicopter Operators and should assist other countries in applying VHM. The material within this guide complements CAP 753. UPDATE 20 October 2017: HeliOffshore updates HUMS Best Practice Guidelines with new annexes. One of the new annexes in Version 1.1 covers the S-92A TR Pitch Change Shaft. A subgroup under the leadership of Jason Alamond, HUMS program manager with Era Helicopters, has produced an annex defining The Ideal HUM System. Meanwhile, another subgroup has developed a framework of key performance indicators (KPIs)… laying the groundwork for operators to be able to share and benchmark HUMS data. The HUMS KPI subgroup was led by Andy Evans, a director with Aerossurance. HUMS Background We have previously discussed several HUMS / VHM (Vibration Health Monitoring) topics: Aerossurance Wins UK Military Aviation Authority (MAA) HUMS Maintenance Credit Contract European Aviation Safety Agency (EASA) HUMS Research Developments EASA & US Federal Aviation Administration (FAA) HUMS / VHM Developments HeliOffshore Launch HUMS Best Practice Guide We have also covered the 2016 HeliOffshore Annual Conference: Offshore Helicopter Safety Performance HUMS Training, Coaching and Improvement Support Aerossurance Director Andy Evans is a former UK CAA former HUMS specialist, JAA Rotors and Transmission Specialist, Secretary of the Helicopter Health Monitoring Advisory Group (HHMAG) and line manager of HUMS at a major offshore helicopter operator. Aerossurance is an active member of HeliOffshore and we have undertaken a number of HUMS technology, regulatory and certification projects...
read moreCanadian KA100 Fuel Exhaustion Accident
Canadian KA100 Fuel Exhaustion Accident The Transport Safety Board of Canada (TSB) has finally issued their report into a fuel exhaustion accident involving Beechcraft King Air 100 (BE10) C-GJSU, operated by Aviation Flycie Inc in Quebec on 10 June 2013. This accident highlights important human factors, competence and regulatory oversight issues. The aircraft was extensively damaged, and the 4 occupants sustained minor injuries. The Accident Flight The flight was to check the rudder trim indicator and investigate a potential synchronisation problem between autopilot and the GPS. The aircraft … …took off from the Montréal/St-Hubert Airport, Quebec, on a local flight under visual flight rules with 1 pilot and 3 passengers on board. As the aircraft approached Runway 24R at the Montréal/St-Hubert Airport, both engines (Pratt & Whitney Canada, PT6A-28) stopped due to fuel exhaustion. The pilot diverted to the St-Mathieu-de-Beloeil Airport, Quebec, and then attempted a forced landing in a field 0.5 nautical mile west of the St-Mathieu-de-Beloeil Airport. The aircraft struck the ground 30 feet short of the selected field and slid on its belly 120 feet before coming to a stop perpendicular to the approach path. The Operator TSB explain that: At the time of the accident, Aviation Flycie Inc. was a recently formed company. Its owners filed a statement of intent with TC in August 2012 to operate a commercial air service. On 26 March 2013 [less than 3 months before the accident], Aviation Flycie Inc. commenced business under CARs Subpart 703 using a single BE10 aircraft. The chief pilot was the company’s only pilot-in-command, and had trained the PRM [person responsible for maintenance] as co-pilot before the company began flight operations. Therefore, when commercial flights were first conducted, the company had 3 employees in operations and a co-founder in sales and administration. A second co-pilot was hired approximately 2 weeks later. The Accident Investigation – Misreading the Fuel Quantity TSB say: While preparing for the flight, the pilot relied exclusively on the fuel gauges, misread them [the aircraft had adjacent main wing and auxiliary nacelle tank gauges], and assumed that the aircraft had enough fuel on board for the flight. They explain that at departure… …the wing tanks were empty, and each of the nacelle tanks contained approximately 130 pounds of fuel. Although the gauge indicator needles were showing slightly more than ¼ tank of fuel in each nacelle tank, the needles were positioned at the midpoint of the dial because of the non-linear graduation scale of the gauges. Seeing the needle at the midpoint of the dial could have led the pilot to conclude that the tanks were half full. Further, although the fuel gauges of the wing tanks are similar to those of the nacelle tanks, the graduation scales of the 2 types of gauges differ. The “F” position on each fuel gauge dial represents 871 pounds in the wing tanks, but 382 pounds in the nacelle tanks. Similarly, the midpoint of the dial represents 310 pounds in the wing tanks, but 130 pounds in the nacelle tanks. Based on these gauge characteristics, it was hypothesized that the pilot might have established a false equivalence between the visual position of the needle and the total quantity of fuel in the tanks. However, given that the sum of 2 half-full nacelle tanks would have been about 382 pounds of fuel and the pilot estimated that 580 pounds remained, that hypothesis was ruled out. A second hypothesis examined whether a...
read moreYuma Hawk Accident: Lessons on Ex-Military Aircraft Operation
Yuma Hawk Accident: Lessons on Ex-Military Aircraft Operation A fatal accident with an ex-Korean Hawk, operated by a defence contractor, highlights some of the issues of civil use of ex-military aircraft. On 11 March 2015, the BAe Hawk Mk 67 (known in Korea as a T-59), N506XX, operated by Air USA, struck a vehicle after a stall during take off at the joint military / civil airfield at Yuma, AZ. The driver of the vehicle died in the crash. The two occupants of the Hawk (pilot and passenger) were not injured but the aircraft was destroyed by fire. The Republic of Korea Air Force (ROKAF) had ordered 20 Hawk Mk67s in July 1991. They were retired in 2013 with Air USA purchasing 12. The aircraft had an Experimental Certificate of Airworthiness and was being operated as a Public Aircraft (effectively the FAA equivalent of a civil ‘State Aircraft’, to use ICAO terminology), on contract to the US Air Force (USAF) in support of a Special Operations Terminal Attack Controller Course (SOTACC). The Accident Flight and the Aircraft Configuration The US National Transportation Safety Board (NTSB) in their investigation report, explain N506XX was one of a pair performing a 15-second staggered takeoff from runway 03L, to provide close air support for the training of Joint Terminal Attack Controllers (JTAC‘s). It was equipped with external fuel tanks on the inboard wing pylons, and SUU-20 Bomb Dispenser/Rocket Launchers (on loan from the USAF), loaded with practice ordinance, on the outboard pylons. The NTSB comment: The external fuel tanks were partially filled with fuel, which was allowed per the airplane’s flight manual… The SUU-20 had not been evaluated by BAe and was not listed as an approved device in the Hawk Weapons Manual, and as such in April 2014, Air USA commissioned an FAA Designated Engineering Representative (DER) to prepare a structural comparison report to assess the viability of installing the SUU-20, along with a series of other non-BAe evaluated munitions and stores. The report utilized the comparative dimensions of the CBLS-200, MK-83 free fall bomb, and the fuel tank. The MK-83 was nearly identical in length to the SUU-20, and weighed 987 pounds. Any intended use of the fuel tank as a basis for comparison was erroneous, as the tank was not capable of being fitted to the outboard pylon. The report was structural only in nature, and did not take into account the aerodynamic effects of utilizing the alternate munitions and stores. The report concluded that the use of the alternate stores was, “structurally satisfactory.” It is possible that the airplane’s stall margin was eroded further by the use of the alternate dispensers… The NTSB say that the pilot was “unable to maintain airplane control following rotation. The airplane did not climb, departed the left side of the runway, and struck a pickup truck”. A United States Marine Corps (USMC) construction crew was next to runway 03L preparing for the installation of an expeditionary arresting gear system (as shown below in use in the Pacific): https://www.youtube.com/watch?v=gxzzmtbcOec The NTSB say: The pad was located 10 feet from the runway edge, about 6,500 feet from the runway 03L landing threshold. The construction operation, which included support vehicles, crew, and construction equipment, occupied the space from the runway pad outwards about 150 feet. The truck that was struck was located 140 feet beyond the runway edge, and was occupied by a Marine...
read moreAborted Take Off with Brakes Partially On Results in Runway Excursion
Aborted Take Off with Brakes Partially On Results in Runway Excursion The crew of a Cessna 550 (Citation Bravo) VH-FGK did not detect anything abnormal during the take-off roll until they attempted to rotate. After trying full back-pressure without a change in pitch the captain rejected the take-off. The crew applied full braking and reverse thrust, but the aircraft overran the runway. The nose landing gear collapsed and the aircraft sustained substantial damage. The crew, the only occupants, uninjured. ATSB Safety Investigation In their investigation report into the accident, which occurred on 25 September 2015, the Australian Transport Safety Bureau (ATSB) say: The aircraft did not accelerate normally as the acceleration was retarded by drag associated with rolling friction. This was indicative of partial brake pressure remaining during the take-off run. The partial brake pressure was possibly due to the parking brake being selected on at the holding point with enough pressure to retard aircraft acceleration during the take-off, but not sufficient to prevent the aircraft reaching rotate speed. Furthermore, the nose-down moment generated by the partial brake pressure probably prevented the aircraft rotating sufficiently to become airborne, despite normal nose-up elevator deflection. Heat in the brakes due to partial pressure during the take-off run may have reduced their effectiveness when the captain rejected the take-off, contributing to the runway overrun. The ATSB go on to explain: The parking brake was set by either pilot applying and holding footbrake pressure and [in addition] the pilot in the left (captain’s) seat pulling out the parking brake lever underneath the left instrument panel. The lever could be selected OFF or fully ON. There was no partial release position of the lever. When the lever was pushed forward from the ON position, pressure in the lever would continue to release the lever until it was [fully] in the OFF position. The position of the parking brake lever was not visible to the pilot in the right seat. There was no cockpit annunciation that the parking brake lever was in the ON position. This design would not be compliant with 25.735 Amendment 25-107 but this was issued in 2002, after the Cessna 550 was certified. Previous Incidents In 2010, a Cessna Citation CJ1, registered N646VP, overran the runway at Leeds Bradford Airport, West Yorkshire, UK. During the take-off run, the pilot assessed that the aircraft would not accelerate to V1 and rejected the take-off. As the pilot braked, both brakes failed, the right brake caught fire and the aircraft overran the end of the runway. The accident investigation by the UK Air Accident Investigation Branch (AAIB), and reported in AAIB Bulletin 3/2011, concluded that the brakes were probably on, at least partially, during the take-off run. The US National Aeronautics and Space Administration (NASA) provided the ATSB with a report of Cessna Citation parking brake engaged or partially engaged during takeoff roll incidents from the Aviation Safety Reporting System (ASRS). This included the following two reports: A Cessna 525 [Citation CJ1] owner/pilot reports hiring a professional pilot to fly him to an airport due to a strong gusty wind forecast. The professional pilot forgets to release the parking brake prior to take-off and this omission is not detected until airborne. Upon landing the right brake is locked and the right tire fails causing directional control problems. On landing, a Cessna 550 blew both main...
read moreNTSB Report on Puerto Rico SA-227 Metro III LOC-I – 2 Dec 2013
NTSB Report on Puerto Rico SA-227 Metro III LOC-I – 2 Dec 2013 IBC Airways Fairchild SA-227 Metro III N831BC was performing a cargo flight from Santo Domingo (Dominican Republic) to San Juan (Puerto Rico) on 2 December 2013. It suffered a Loss of Control – Inflight (LOC-I) and structural break-up according to a recently issued US National Transportation Safety Board (NTSB) report. Both crew died and the aircraft was destroyed. About 40 minutes into the flight in night visual meteorological conditions the aircraft was cleared for a a descent to 3,000 ft: During the descent, about 7,300 ft and about 290 kts, the airplane entered a shallow left turn, followed by a 45-degree right turn and a rapid, uncontrolled descent, during which the airplane broke up about 1,500 ft over uneven terrain. Among the challenges faced by the NTSB was that the aircraft: …was not equipped with a flight data recorder or cockpit voice recorder (CVR) (although it previously had a CVR in its passenger configuration) nor was it required by Federal Aviation Administration (FAA) regulations. There were also no avionics on board with downloadable or nonvolatile memory. As a result, there was limited information available to determine what led to the uncontrolled descent or what occurred as the flight crew attempted to regain control of the airplane. This does point to a weakness in Federal Aviation Regulations for small cargo aircraft, that could be especially significant when hampering investigations into technical failures that could hazard passenger aircraft. The NTSB investigation established: There was no evidence of any in-flight mechanical failures that would have resulted in the loss of control, and the airplane was loaded within limits. During the accident sequence both wings failed upwards: As the wings failed, the propellers simultaneously chopped through the fuselage behind the cockpit [and] the horizontal stabilizers…also failed upward. Evidence also revealed that, at some point, the flight crew lowered the landing gear. Although it could not be determined when they lowered the gear, it could have been in an attempt to slow or regain control of the airplane during the descent. The NTSB examined past occurrences elsewhere: Other similarly documented accidents and incidents generally involved unequal fuel burns, which resulted in wing drops or airplane rolls. However, in the current investigation, the fuel cross feed valve was found in the closed position, indicating that a fuel imbalance was likely not a concern of the flight crew. In at least two other events, unequal fuel loads also involved autopilots that reached their maximum hold limits, snapped off, and rolled the airplane. Although the airplane in this accident did not have an autopilot, historical examples indicate that a sudden yawing or rolling motion, regardless of the source, could result in a roll, nose tuck, and loss of control. The roll may have been recoverable, and in one documented case, a pilot was able to recover the airplane, but after it lost almost 11,000 ft of altitude. The NTSB say that in this case: Although reasons for the loss of control could not be definitively determined, the lack of any preexisting mechanical anomalies indicates a likelihood of flight crew involvement. Then, during the recovery attempt, the flight crew’s actions, while operating under the difficult circumstances of darkness and rapidly decreasing altitude, resulted in the overstress of the airplane. The National Transportation Safety Board determined the...
read moreHelicopter Ops and Safety – Gulf Of Mexico 2015 Update
Helicopter Ops and Safety – Gulf of Mexico 2015 Update The Helicopter Safety Advisory Conference (HSAC) has been publishing data on the Gulf of Mexico (‘GOM’) offshore helicopter fleet and its safety since 1995. We looked at their 2014 data previously and now examine their 2015 data. Helicopter Operations: GOM Fleet Data HSAC report that flying activity is in decline, with just under 228k flying hours in 2015 (vs 298k in 2014 and 410k in the peak year of 2007), using 346 helicopters (vs 415 in 2014). Flying hours, passenger numbers and flights have dropped by 28%, 20% and 34% respectively over the last 5 years. These helicopters were operated by 10 companies (vs 13 in 2014). The big three are Bristow, ERA and PHI, with RLC strong in the single engine sector. The number of smaller helicopters continues to decline with single engine helicopters down 38% over 5 years, light twins 33% and medium twins 26%. The number of heavy twins (mainly Sikorsky S-92As) however has doubled in the last 5 years to 50 (up 4 since 2014). This is indicative of the economic decline in the small ageing coastal fields and more deepwater exploration and production (as demonstrated by the last few seconds of the animated map below, a 2008 MMS report and a deepwater field status listing). In 2015 the average utilisation was: Single engine – 711 flying hours with an average 19 minute sector length (vs 590 flying hours and 20 mins in 2014) Light twin – 460 flying hours with an average 19 minute sector length (vs 441 flying hours and 17 mins in 2014) Medium twin – 606 flying hours with an average 33 minute sector length (vs 794 flying hours and 38 mins in 2014) Heavy twin – 715 flying hours with an average 35 minute sector length (vs 805 flying hours and 36 mins in 2014) The medium / heavy twin usage per aircraft is approximately 20% less that the average for the UK North Sea fleet, partly due to the greater use of pooled aircraft to meet sole use contracts in Europe. The decline in medium and heavy usage suggests that similar arrangements at some of the larger bases could result in cost savings. Helicopter Safety GOM HSAC say there were three accidents in 2015, all non fatal (vs 4 in 2014, one fatal). The US National Transportation Safety Board (NTSB) however reports four, all involving single engine helicopters: NTSB Identification: CEN15LA156 On February 20, 2015, about 0750 central standard time, an AgustaWestland AW119 MK II [Koala] helicopter, N802SM, experienced an abrupt, uncommanded left yaw during cruise flight over the Gulf of Mexico. The pilot and three passengers were not injured. The helicopter sustained substantial damage. The helicopter was registered to and operated by Era Helicopters LLC., under the provisions of 14 Code of Federal Regulations Part 135 as an on-demand air taxi flight. Visual meteorological conditions prevailed for the flight which operated on a company visual flight rules flight plan. The flight departed the Houma-Terrebonne Airport (HUM), Houma, Louisiana. After the uncommanded left yaw, the pilot returned to HUM and performed a run-on landing. A post-flight inspection of the helicopter revealed one of the tail rotor pitch change links was fractured. No additional damage to the helicopter was discovered. The pitch change link was retained for further examination. UPDATE 29 November 2016: Probable Cause: The fracture of the tail rotor pitch change link due to excessive bearing rotational friction, which resulted from the bearings being installed in exceedance of the maximum allowable torque during the last...
read moreFirst Martin-Baker Ejection In-Flight in 1946
First Martin-Baker Ejection In-Flight in 1946 In 2016 UK company Martin-Baker Aircraft celebrated the 70th anniversary of the first in-flight ejection with one of their ejection seats. On 24 July 1946, Martin-Baker’s Bernard Lynch successfully ejected from the rear cockpit of a specially modified Gloster Meteor F3 at 320 mph IAS at 8000 ft as part of development testing. Lynch had made the first ground test 24 January 1945 and made 30 test ejections in total. The first emergency use of a Martin-Baker seat took place on 30 May 1949. Test pilot Jo Lancaster DFC was forced to eject from an Armstrong Whitworth AW52 prototype using a pre Mk1 ejection seat over Southam, Warwickshire. UPDATE 11 August 2019: Lancaster passed away on 10 August 2019 at the age of 100. Martin-Baker were not the first to develop and deploy ejection seats. Compressed gas and explosive fired seats have been developed in Germany and Sweden during WWII. However the explosive, and later rocket, powered Martin-Baker seats have become the most widely used worldwide, with a market share of around 55%. Martin-Baker Today Martin-Baker remains family run business, jointly managed by the twin sons of the late founder, Sir James Martin, and headquartered in Denham. The company has manufactured over 70,000 seats and have around 17,000 seats currently installed on 51 aircraft types with 88 operators. To date 7497 people have been saved by Martin-Baker seats around the world. The company continues to use military registered Meteors as test aircraft. UPDATE 9 February 2017: Ejection Seat Market Is Changing Pace UPDATE 10 February 2017: Martin-Baker’s Test Meteors Are Still Going Strong UPDATE 19 May 2020: A 1950s ejection seat safety film: Resources: Flight history of Martin-Baker from 1965 British Pathe news reel from 1952 User stories on Pinterest https://youtu.be/9IfXIrWztBY https://www.youtube.com/watch?v=m6HoIRoYlXM https://www.youtube.com/watch?v=v8spBgCo43Q&fbclid=IwAR028GHKRDwh7BwD4UY6KD59e1dRaVC2SHeWANFo-31VMbfXS6KLfAiKdoI Aerossurance is highly experienced in military aircraft design, safety and regulation. For practical aviation advice you can trust, contact us at: enquiries@aerossurance.com Follow us on LinkedIn and on Twitter @Aerossurance for our latest...
read moreFatal Flaws in Canadian Medevac Service
Fatal Flaws in Canadian Medevac Service The Transportation Safety Board of Canada (TSB) has released its investigation report into the Controlled Flight into Terrain (CFIT) during a flight of a medevac Piper PA-31 Navajo C-GKWE, operated by Atlantic Charters on charter to Ambulance New Brunswick (ANB), in Grand Manan, NB in darkness on the morning of 16 August 2014. The aircraft was returning from delivering a patient to St John, NB with two crew and two medical personnel aboard. While attempting to land the crew initially conducted a missed approach. During a second approach, the aircraft touched down about 450 metres from the runway threshold. The aircraft continued through about 30 metres of brush before becoming airborne briefly and impacting left of the runway centreline about 300 metres from the threshold. the Aircraft Commander and a passenger were killed, the First Officer and the other passenger received serious injuries. The aircraft was destroyed. The TSB made the following as to causes and contributing factors: The captain commenced the flight with only a single headset on board, thereby preventing a shared situational awareness among the crew. It is likely that the weather at the time of both approaches was such that the captain could not see the required visual references to ensure a safe landing. The first officer was focused on locating the runway and was unaware of the captain’s actions during the descent. For undetermined reasons, the captain initiated a steep descent 0.56 nautical mile from the threshold, which went uncorrected until a point from which it was too late to recover. The aircraft contacted a road 0.25 nautical mile short of the runway and struck terrain. The paramedic was not wearing a seatbelt and was not restrained during the impact sequence. The TSB note that approach-and-landing accidents are on the their Watchlist and that this accident: …involved several of the most common factors associated with CFIT accidents. In particular, it involved a non-precision instrument approach conducted at night over a dimly lit, sparsely populated area, and with limited visibility in fog. This article is not going to examine the cause of the CFIT further. Instead we will look at some other factors that emerged during the TSB investigation. The Operator The TSB say that Atlantic Charters had been operating from Grand Manan since 1982 and: The owner and founder of the company, who was also the occurrence captain, held the positions of accountable executive, operations manager, chief pilot and maintenance coordinator. Atlantic Charters conducts CARs subpart 703 air taxi operations, providing domestic and international air charters. The company had been providing patient transfer charter services for over 30 years, with the majority of this work being carried out as single-pilot operations. At the time of the accident, the company employed 5 pilots, including the owner and a member of the owner’s family. With the exception of [the family members] the company typically hired pilots with limited flying experience who normally stayed with the company for about 2 years before moving on. Atlantic Charters did not have a safety management system (SMS), nor was it required by regulation to have one. There was no documented flight safety program at Atlantic Charters. The Customer ANB’s Air Ambulance Service (‘AirCare’) consists of a contracted fixed-wing aircraft and crew. AirCare has been provided by the same operator since before ANB was established in 2007. ANB’s contract with Atlantic Charters requires 2 pilots who are certified and qualified to operate the type of aircraft...
read moreUncontained PW1524G Failure During CS100 (A220) Certification Testing
Uncontained PW1524G Failure During Bombardier CS100 (now Airbus A220) Certification Testing The Transportation Safety Board of Canada (TSB) has recently issued its investigation report, into an uncontained engine failure and fire during certification ground testing of Bombardier CS100 (now the Airbus A220-100) C-FBCS on 29 May 2014 at Montréal International (Mirabel) Airport. The crew immediately shut down the Pratt & Whitney PW1524G engine and evacuated the aircraft safely, but the engine and aircraft sustained substantial damage. The Aircraft and Engine The TSB explain: Bombardier announced the development of the C Series aircraft in July 2004. Two variants of the C Series aircraft are offered: the 108–125 passenger CS100 and the 130–160 passenger CS300. The PW1524G is a twin-spool, axial-flow, ultra-high–bypass ratio geared turbofan engine that includes core-mounted angle and main gearboxes. It is part of the PW1000G family of geared turbofan engines that were first run in 2008; the family comprises variants ranging from 15 000 pounds (66.75 kilonewtons [kN]) to 33 000 pounds (146.85 kN) of static thrust. The PW1524G variant, specifically developed for the C Series aircraft, delivers 24 400 pounds (108.5 kN) of thrust. The Investigation TSB describe the failure mode as follows: The investigation determined that “heat soaking,” as a result of insufficient cooldown, caused the seal of a bearing oil feed tube to fail. It was determined that the engine had been shut down after high power operation, without sufficient time for its internal temperatures to reduce at lower power. As a result, when the seal failed, it allowed engine oil to mix with the turbine rotor’s cooling air flow. The resulting air/oil mixture ignited due to high ambient temperatures… …and the ensuing combustion caused the entire [Low Pressure] turbine rotor stage to fail. This resulted in major damage to the engine, nacelle and wing. This damage included: The [failed engine’s] left side thrust link was severed in line with the LPT [Low Pressure Turbine] plane; some engine-air and -oil lines, as well as some electrical wires and fire detection loops, were damaged or severed in the vicinity of the LPT case breach. The left-wing structure sustained major debris impact damage when a segment of the first-stage LPT rotor disk 28 inches long penetrated the wing’s centre fuel tank. The impact created a span-wise gash 33 inches long and 3 inches wide in the carbon composite lower skin plank, inboard of the engine…with a total delamination area of 16 × 37 inches. The turbine disk segment then partially exited through the upper wing plank, where it remained stuck, creating a hole approximately 13 × 7 inches, with a total delamination area of 21 × 10 inches. Signs of burning were found around the hole, although the fuel contained in the tank did not ignite. The TSB explain that: From its initial release until the issuance of the engine’s type certificate by TC [Transport Canada], the Pratt & Whitney PW1500G installation and operating manual (IOM) specified a 10-minute cooling period before shutdown in order to minimize the potential for oil coking in the main engine bearing compartments and to mitigate a bowed rotor start condition. This cooling period was determined based on the results of testing carried out on development engines and demonstrated compliance with the PW1500G’s certification basis. [PWC] issued a Restriction and/or Special Instruction (RSI) with cooling procedures for their engines before shutdown, with alternate solutions for hot shutdowns. Bombardier interpreted the alternate solutions in the RSI as an...
read moreCarrier Arrestor System Maintenance Errors
Carrier Arrestor System Maintenance Errors Eye watering video has emerged of a mishap on the US aircraft carrier USS Dwight D. Eisenhower (CVN 69) in the Atlantic on 18 March 2016. The 1½-inch-thick steel arrestor wire failed during the landing of a Northrop Grumman E-2C Hawkeye and during the go-around the E-2C drops out of sight below the deck edge before climbing away. The investigation highlighted shortcomings in maintenance data. Eight sailors on deck suffered a variety of injuries from the flailing cable, including a fractured skull, facial, ankle, wrist, pelvis and legs with one sailor receiving a possible traumatic brain injury. A Northrop Grumman C-2A Greyhound and a Sikorsky MH-60S Seahawk helicopter parked on deck also received about $82,000 in damage. Safety Investigation According to a US Navy investigation report obtained by The Virginian-Pilot through a Freedom of Information Act request: … maintenance personnel missed at least one and possibly two “critical steps” while working on an engine that helps operate the carrier flight deck’s cables, which are called cross deck pendants, after a previous landing. As a result, the engine failed to slow the aircraft, instead causing the pendant to break “at or near” the Hawkeye’s tailhook. The report said that while there was a “lack of procedural compliance” while troubleshooting an error code from a previous arrested landing, “the sailors involved reasonably believed they had properly and conscientiously completed the complicated procedure.” The maintenance personnel: …were using an approved Navy procedure when they missed steps that led them to misprogram a valve that controls the gear engine’s pressure and energy absorption, according to the report. But that procedure lacked warnings, other notations and wasn’t “user friendly,” Navy investigators found. As a result, while those personnel failed to comply with a “technically correct written procedure,” the Navy found their error understandable because the procedure didn’t explain the basis for its steps, lacked supervisory controls and “failed to warn users of the critical nature” of the valve’s realignment. A command investigation into the incident included recommendations for the development of additional controls for troubleshooting the carrier’s aircraft recovery system as well as a review of the system’s procedures to add necessary warnings, cautions and quality assurance. However, disappointingly, despite recognising the shortcomings in the maintenance data and that “the sailors involved reasonably believed they had properly and conscientiously completed the complicated procedure”: It also included recommendations that Capt. Paul Spedero, commanding officer of the Ike, consider formal counseling, fitness evaluations, qualification removal, requalification or administrative actions for three others whose names were redacted. Other Safety Resources James Reason’s 12 Principles of Error Management 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. UPDATE 9 November 2016: USMC CH-53E Readiness Crisis and Mid Air Collision Catastrophe UPDATE 8 February 2018: The UK Rail Safety and Standards Board (RSSB) say: Future safety requires new approaches to people development They say that in the future rail system “there will be more complexity with more interlinked systems working together”: …the role of many of our staff will change dramatically. The railway system of the future will require different skills from our workforce. There are likely to be fewer...
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