King Air 100 Uncontained TPE331-6 Failure – Inappropriate Repair Scheme
Beech KA100 Uncontained TPE331-6 Failure – Inappropriate Repair Scheme (N6756P) On 16 July 2014 Beechcraft King Air 100 N6756P suffered an uncontained failure of its no 1 Honeywell TPE331-6 turboshaft engine near Bakersfield, California during a private flight. The US National Transportation Safety Board (NTSB) explain in their safety investigation report (issued 22 September 2020, 74 months later) that the aircraft… …was cruising at flight level 190 (19,000 feet amsl), about 30 miles ENE of Bakersfield, when the left engine spooled back. The pilot executed the engine failure in-flight procedures and landed uneventfully at Meadows Field Airport. Post flight inspection revealed damage, consistent with an uncontained engine event, to the left nacelle and external damage to the left engine. Engine Examination and Failure Mode …examination of the left engine revealed an overload failure of the 2nd-stage turbine wheel. The investigation determined that a repair to a brazed joint on the 2nd-stage main nozzle casting support baffle and outer flange had failed. Once the seal ring fractured, it sprang open slightly from normal internal stresses, became loose in the cavity, and then migrated axially aft until it contacted the rotating 2nd-stage turbine wheel web and started to machine the web material, weakening it until the overload failure occurred. According to the engine manufacturer, without the cooling air, metal temperatures of the knife-edge seal ring at the forward and aft ends were estimated to be 1446°F and 1263°F, respectively. Intergranular fractures were initiated after exposure to these high temperatures. The nominal cavity temperature should be 1060°F. Maintenance History and Repair Approval The 2nd stage stator assembly forward braze joint was repaired by Texoma Turbines, in Durant, Oklahoma in February 2009. Honeywell do not consider the part repairable. However, a Repair Process Specification (RPS) had been developed independently. NTSB also noted that: The original technical documents used to substantiate the repair processes in the RPS could not be located, therefore a review of it could not be done. An FAA technical staff member interviewed from the Fort Worth ACO Branch, believed that there was no technical substantiation data written for this repair and that only the process steps were written by the original DER [Designated Engineering Representative] because the technical substantiation data was not included in the DER’s approval. It is not known if the DER considered (1) the braze joint oxidation and porosity sensitivity to welding and heat-treatment heat or (2) of the impact of loss of cooling air of this part on any adjacent or downstream components of the engine. The technical substantiation data should have been retained by the original DER and the original Repair Station; however, he was no longer a DER and not in the DER directory. Guidance for the retention of technical substantiation documents is defined in FAA Order 1350.15C, Records Management, Chapter 11, Flight Safety, Item 8113 Designated Engineering Representative states that original document destruction is not authorized. There is no guidance for the transfer of documents when a DER quits or dies. NTSB Probable Cause The failure of the 2nd-stage turbine wheel due to an improper repair of the 2nd-stage stator assembly, which the manufacturer does not consider a repairable item. Contributing to the incident was the designated engineering representative’s approval of the repair process. Safety Resources Also see these Aerossurance articles: NDI Process Failures Preceded B777 PW4077 Engine FBO Japanese Jetstar Boeing...
read moreB206B Hit by Truck in Forced Landing after 16 Months of Operation with Unairworthy Engine
B206B Hit by Truck in Forced Landing after 16 Months of Operation with Unairworthy Engine (Bell 206B PT-HPG) On 11 February 2019 Bell 206B PT-HPG, operated by RQ Serviços Aéreos Especializados, suffered an engine power loss while en route from the Royal Palm Plaza Helipad (SSQW) to the Campinas to the Bandeirantes Helipad (SDBH) in São Paulo, Brazil. Investigators of the Brazilian Centro de Investigação e Prevenção de Acidentes Aeronáuticos (CENIPA) explain in their safety investigation report, issued on 29 October 2020, that CCTV footage showed that the pilot attempted to autorotate alongside the Rodoanel Mário Covas highway. https://youtu.be/EuUYHGta9TY?t=11 However, the aircraft descended the two bridges and was hit prior to touch down by a truck travelling on the access road to the highway, shortly after leaving a toll plaza. Remarkably, the truck driver was uninjured. The pilot and the passenger, journalist and news anchor Ricardo Boechat, both died. Much of the helicopter was destroyed in a post-crash fire. It is reported that Ricardo Boechat was on his way back to the head office of the broadcaster BandNews FM in São Paulo after speaking at an event for pharmaceutical company Libbs. The flight had been arranged by contracted by Zum Brazil, an event company, working for Libbs. CENIPA Safety Investigation CENIPA determined that the weather was suitable for VFR flight. They believe that the pilot was aiming to autorotate on to an area of grass between two carriageways. However, the aircraft overshot that area and descended between the two bridges onto the road below. The aircraft was hit on its left side, in flight, by a truck…and broke into four parts: Main Gearbox (MGB), blades, engine, fuselage and tail boom. After the collision, a fire completely destroyed the fuselage and partially destroyed the MGB, blades and engine. Although the aircraft’s fuel was destroyed in the fire, fuel contamination was ruled out after sampling the airport bulk fuel system and the bowser at the airfield the helicopter was last refuelled. The Rolls-Royce M250 turboshaft engine was examined. During the separation of the compressor section and the Gearbox, bearing nº 2 was found locked and with the ball separator fractured in several parts. It was possible, through the markings on bearing nº 2, to identify that it was a Parts Manufacturer Approval (PMA) component, with design and production approved by the FAA, manufactured by Timken Alcor Aerospace Technologies Inc [owned by Kaman since 2015]. It was not possible to identify when this bearing was fitted. The Bearing nº 2 was subjected to stereoscopic examinations…and it was evidenced wear and loss of material in the external and internal bearing races. Fine metal powder was found in the filter and both engine Magnetic Chip Detectors “contained a significant amount of apparently ferrous material”. The debris was tested and consistent with M50 bearing material. The oil delivery tube, P/N 6851505 and S/N BN 13509, was visually inspected and it was found that there were residues of foreign material in the orifice responsible for supplying oil for lubrication of bearing nº 2. A test was carried out, introducing oil at low pressure, and it was verified that there was no fluid coming out of the hole that directed the lubrication to bearing nº 2. Further lab examination confirmed the tube was blocked with carbon debris. CENIPA report that: During the investigation, despite requests made to the operator, it was not possible to locate and access the entire maintenance records of the PT-HPG aircraft. They were able to...
read moreDeadly Dusk Air Ambulance Bird Strike
Deadly Dusk Air Ambulance Bird Strike (Air Methods, B407, N620PA) On 19 November 2017 Air Methods Corporation (AMC) air ambulance Bell 407 N620PA crashed south of Stuttgart, Arkansas. The helicopter was en route in Visual Meteorological Conditions (VMC) from Pine Bluff, Arkansas to pick up a patient in Helena, Arkansas. The pilot and two medical personnel on board were fatally injured. The US National Transportation Safety Board (NTSB) explain in their safety investigation report that: The helicopter was transmitting its position to the company via satellite communications. At 1855:50, the helicopter transmitted that it was heading 070°, travelling 116 knots at 1,252 ft mean sea level [so c 1,000 ft AGL]. This was the last recorded data point. Air Methods informed the NTSB that: Air Force SAR advised Company Operational Control Center of an ELT activation for the aircraft at 2015. The aircraft wreckage was located by local law enforcement some time prior to 2100, in a rural area approximately 22 nm ENE of the Pine Bluff Regional Airport (KPBF). The terrain in the crash area is…relatively flat, with mixed woodland and meadow terrain features. The aircraft had just passed over the 33,832 acre Bayou Meto State Game Area to the west. Witnesses reported ‘thousands’ of geese in the local area. NTSB Safety Investigation A weather study conducted for the accident area did not reveal any weather hazards around the time of the accident. Both the sun and the moon were more than 15° below the horizon, and dark night conditions existed with no illumination from the moon. The helicopter was found on the bank of a reservoir on its right side…. All major components of the helicopter were accounted for at the site. A post-impact fire consumed a majority of the fuselage. Fragments of the pilot’s night vision goggles were located in the area of the pilot controls (company policy required pilots and one [medical] crewmember to wear night vision goggles during night flights.) No pre-impact anomalies were detected during postaccident examination of the helicopter airframe or engine. However: During the on-scene portion of the investigation, numerous geese, ducks, and cranes were observed in the reservoir and at another nearby reservoir. Multiple bird remains were found from the cockpit area to the first bulkhead. The Arkansas Crime Laboratory, Little Rock, Arkansas, conducted an autopsy on the pilot. The cause of death was multiple injuries. The autopsy noted white bird feathers embedded in the pilot’s coveralls and right boot. Samples from the bird remains were sent to the Feather Identification Laboratory, Smithsonian Institution, National Museum of Natural History, Washington, DC. In all the lab received 12 bags of debris. These were subjected to DNA and microscopic analysis. Samples submitted to the Smithsonian contained remains from snow geese, which typically have an average weight of 4.8 and 5.48 lbs for females and males, respectively. The NTSB note that: The Bell 407 is certificated under 14 CFR Part 27 as a normal category rotorcraft. As such, there are no bird strike safety requirements for the windshield. Transport category rotorcraft do have a requirement under 14 CFR 29.631 to be designed to ensure capability of continued flight and/or landing, however the design requirement assumed a single 2.2 lbs bird. The accident involved numerous birds in excess of 4 lbs each. A review of the FAA Wildlife Strike Database found a strike report for November 17, 2011, about 0705 [Local Time] the pilot of a Cessna 210 airplane reported striking a snow goose near the area of the accident...
read moreTragic Texan B206B3 CFIT in Dark Night VMC
Tragic Texan B206B3 CFIT in Dark Night VMC (N417WT) On 2 November 2018 private Bell 206B3 N417WT crashed in a Controlled Flight Into Terrain (CFIT) at night just c100 ft below the top of a 1,500-ft hill in the Chalk Bluff Resort and Park, c5 miles east of their departure point at a private ranch, NW of Uvalde, Texas. The pilot and two passengers, who were leaving their wedding reception for their honeymoon, all died. The US National Transportation Safety Board (NTSB) explain in their safety investigation report (issued in June 2020) that the aircraft had departed the ranch 6 mins earlier at 23:41 en route for San Antonio, Texas on a Part 91 ‘personal flight’. The pilot was apparently a family friend and the helicopter was owned by a company that was, in turn, owned by family members. So called night visual meteorological conditions prevailed. However, the moon was below the horizon and the remote rural area would also have had very little cultural lighting on the ground. The pilot was 76, held a Class 2 Medical with certain unspecified waivers/limitations (last examination: 26 March 2018) and had a total of 23,400 flying hours, 400 on type (estimated). It is stated he was Instrument Rated (“Airplane & Helicopter”) and Instructor Rated (“Helicopter & Instrument Helicopter”) though there is no detail on any instrument or night recency. A review of data from the helicopter’s [Chelton] primary and multifunction display units revealed that…the helicopter reached an altitude of 1,900 ft before beginning a gradual descent, until the final barometric altitude of 1,538 ft (indicated altitude on the display) and 74 knots airspeed. The altimeter was set for a barometric pressure of 30.05 inHg. The data did not reveal any extreme changes in pitch, bank, or airspeed. The flight display also retained the last GPS altitude, which was 1,422 ft. Additionally, the terrain awareness warning system (TAWS) and helicopter TAWS low altitude alerts were set for 140 ft above ground level; however, terrain alerts were set to “inhibit”…therefore, the pilot would not have received a terrain warning message. Flight information from the displays did not record any evasive maneuvering, and it is likely that the pilot did not see the terrain before impact…about 71 miles west of San Antonio International Airport. A wreckage path about 75 to 100 yards long was distributed along the hillside leading to the main wreckage. There was no post-crash fire. A search…found the wreckage about daybreak the following morning. No pre-impact aircraft abnormalities were identified by NTSB when the wreckage was examined. Autopsy and toxicology testing did not reveal evidence of pilot incapacitation and there were no traces of alcohol. Based upon the helicopter’s routing the NTSB considered it unlikely that the helicopter encountered reduced visibility or ceilings. The NTSB do note that: A review of the pilot’s medical information indicated that he had been diagnosed with early cataracts; the pilot first reported cataracts to the FAA in 2005, and it is possible that they could have increased in severity enough to have compromised his night vision and contributed to his difficulty avoiding the hill. Of note is that: Video evidence from witnesses who observed the departure showed that bright flood lights were shown [sic – we assume ‘shone’] directly at the helicopter during the departure. [T]he pilot’s eyesight may not have adjusted to the night conditions after being exposed to [the] bright lights during departure. The NTSB say that: However, the severity of his...
read moreLoss of Control During HESLO Construction Task: BEA Highlight Wellbeing / Personal Readiness
Loss of Control During HESLO Construction Task: BEA Highlight Wellbeing / Personal Readiness (AS350B3 F-GKMQ of Air Plus Hélicoptères) During Helicopter External Sling Load Operations (HESLO) on 7 January 2019, Airbus Helicopters AS350B3 F-GKMQ of Air Plus Hélicoptères crashed at Puylaurens, Tarn, killing the pilot. Circumstances of this HESLO Accident The French Bureau d’Enquêtes et d’Analyses pour la Sécurité de l’Aviation Civile (the BEA) explain in their safety investigation report (issued in French on 29 October 2020) that the HESLO tasking was to support construction of communications tower for a telephone company. It involved moving 6 sections of the tower. The helicopter was modified with a window in the cockpit floor (shown above) and a mirror to allow observation of the load and sling during HESLO. It was operating with a 16 m sling attached to three 6 m strops. This technique involves the pilot adopting a particular back posture, linked to the fact that the pilot must tilt his head to the right to look through the floor, while extending the left arm to keep the hand positioned on the collective pitch control. The ergonomics of this type of task may well be relevant as we see below. For this type of construction project: When the load is located about 50 cm from the structure, the technicians rotate it to orient it correctly. Once the load is correctly oriented, the pilot’s assitant [on the ground] gives the order to the pilot to lower the load in contact with the structure. It is then held in place temporarily by means of metal pins before being permanently secured to the structure using bolts. This operation generally lasts about 1 min 30. During this phase, the pilot lowers the helicopter very slightly (about 50 cm) so that the sling is no longer in tension. When the technicians have finished fixing the element, the pilots assitant [on the ground] gives the order to the pilot to release the load. The pilot, 54, had held a Commercial Pilots Licence for 11 years and flow 3,160 hours (3,055 as pilot-in-command). In 2018, he had completed 287 hours, mostly in the AS350 and lifted c 1,600 sling loads that year. He had been employed on a permanent contract by the Airplus Hélicoptères since February 2017. Previously, the pilot worked alone within a company that he had created in 2003 and sold to Airplus Hélicoptères in 2016. He had performed aerial work and local passengers flights, mainly flying Lama and Alouette helicopters. The pilot had a lot of experience in the field of the installation of pylons. He had worked for many years on a recurring basis with the same clients, who knew him well and recognized his skills. The pilot had flown 18 hours for the company in December 2018, spread over 8 working days. On the day of the accident, the pilot was returning from a two weeks [Christmas and New Year] leave. Two sections were successfully positioned in the morning. At lunchtime a company manager arrived to relieve the previous ‘pilot’s assistant’, assigned to work alongside the technicians assembling the tower and be in radio contact with the pilot. The BEA note that the pilot had regularly worked in the past without such assistance however. During the meal, the manager considers that the atmosphere was relaxed and that the pilot seemed neither worried nor tired. After the lunch break, the pilot takes off from the loading area, lifts and position the third section above the structure. Technicians stabilize and secure this section, which the pilot...
read moreAn Uncoordinated Fall from an A320 at Helsinki: How Just Reporting is Not Enough
An Uncoordinated Fall from an A320 at Helsinki: How Just Reporting is Not Enough On 13 January 2020 a cabin crew member was injured in a fall from Finnair Airbus A320 OH-LXD on Stand 913 at Helsinki Airport. The Finnish Safety Investigation Authority (SIAF, the Onnettomuustutkintakeskus) explain in their safety investigation report (issued 28 October 2020 in Finnish with an English summary) that the passengers had already exited the A320 via stairs to a bus… ...and the cabin crew member (CCM4) responsible for the left rear door of the aircraft agreed with the driver of the staircase vehicle that the stairs would be driven away. Because another aircraft was taxiing nearby, the bus could not depart for the terminal immediately, and therefore the staircase vehicle at the rear door could not move either. The senior cabin crew member (SCC) noticed that the bus was not moving and made an announcement to the crew, asking if anyone had given the bus driver the OK sign… The cabin crew member responsible for the rear of the aircraft (CCM2)…hurried to the left rear door of the aircraft, opening it. Because there was no direct visual contact to the bus driver from the door and the staircase vehicle was still in place, the crew member stepped on the top platform of the staircase vehicle to give the sign. While the crew member was stepping back into the aircraft, the staircase vehicle started to move away from the aircraft. As a result, the crew member overbalanced and fell a distance of approx. 3.5 m from the door to the apron, suffering severe injuries. There were no eyewitnesses to the accident, but immediately after, the situation was noticed by the driver of the stairs and the CCM4. Finnair’s cabin crew have been instructed to call for help in Finland by calling the emergency number 112. As for the flight crew, they have been instructed to contact air traffic control with the aircraft radios. In the accident, SCC notified the cockpit about the fall, from which the captain reported the incident to Finnair’s Hub Control Centre (HCC), which then called 112 [at 07.05.20]. First responders were on scene at 07.11.53. The injured cabin crew member had worked for the airline for c20 years. During the safety investigation it was established that: In Finnair’s handbooks and instructions, the duties and areas of responsibility of the cabin crew have been defined in several places. CCM2, who was injured in the accident, believed that she was responsible for giving the OK sign, even though CCM4 had already given the sign to the staircase vehicle driver. In the accident, only CCM4 was aware that the OK sign had been given, meaning that the situational awareness of the crew was not at the same level at the time of the accident. There are belts that can be, and was in this case were, deployed at the top of the last step before the upper platform and at the bottom. They have microswitches and if open prevent the stairs from being driven off. The driver of the stairs does not have a direct line of sight to the upper level of the stairwell, and thus cannot know if anyone is on the pltaform. For the driver, closing the airplane door [also] serves as a sign…that it is safe to drive off. In relation to airport...
read moreFriendly Fire: Civilian Shot in the Head During USAF F-16 Training
Friendly Fire: Civilian Shot in the Head During USAF F-16 Training During night training, on 31 January 2017, US Air Force (USAF) Lockheed Martin F-16C 88-0496 fired 155 20mm cannon shells at the Red Rio bombing range, within the White Sands Missile Range in New Mexico. The strafing however was not directed at the intended target, a simulated SA-8 missile site, but at the supporting Joint Terminal Attack Controller’s (JTAC) Observation Post (OP) 897 m away. A shell fragment hit a civilian contractor in the head, killing him. A US JTAC was also injured. This accident attracted attention in October 2020 when it was reported that the contractor’s widow was awarded $24.6 million after a wrongful death court case. Follow-up reporting suggests that while $24.6 million was claimed, the family settled for less, though their lawyer stated that the family “have enough to take care of them for the rest of their lives”. We look at the facts behind the headlines, critique a USAF human factors analysis and consider if this was a case of ‘What-You-Look-For-Is-What-You-Find’ (WYLFIWYF). USAF AIB Investigation The USAF Accident Investigation Board (AIB) had previously released its investigation report. This is not a safety investigation to identify improvements but a… …legal investigation to inquire into all the facts and circumstances surrounding this Air Force aerospace accident, prepare a publicly releasable report, and obtain and preserve all available evidence for use in litigation, claims, disciplinary action, and adverse administrative action. Arguably such a report is not truly independent as it is written by what may be, and in this case was, a party in litigation. In contrast, safety investigation reports, the ones that identify improvements, are not publicly released by USAF (indeed the family’s claim was based heavily on the AIB report). However, the AIB report does give extensive detail to better understand the context of this accident. Key Personnel The AIB explain that what they term the mishap pilot (MP) and mishap instructor pilot (MIP) were from the 311th Fighter Squadron (311 FS), an F-16 training unit of the Air Education and Training Command (AETC) 54 Fighter Group (54 FG), based at Holloman AFB, New Mexico. The MP was a USAF First Lieutenant, with 86 total flying hours, 60.9 in the F-16…enrolled in the F-16 basic course (B course). The B course is a six-month training course where first-time fighter pilots learn to fly and employ the F-16 . The MP accumulated 6.2 hours flying with night vision goggles (NVGs) and 5 total night sorties prior to the mishap. The squadron commander, director of operations and the MP’s flight commander testified that the MP was an average to slightly-above average student up to the night of the mishap. He was flying his first night CAS sortie, wore Night Vision Goggles, and operated the mishap aircraft equipped with a LITENING Gen4 SE targeting pod, a 500-pound inert laser-guided bomb, and 210 rounds of 20mm TP. The M55A1 and M55A2 target practice (TP) rounds are is ball ammunition, with a body made of steel, but hollow without a filler. The projectile itself is c 100 g. The M61 Vulcan cannon has a muzzle velocity of 1,036 m/s (3,400 ft/s). The MIP was a USAF Captain, stationed at Holloman AFB, with 887 total flying hours, 857 F-16 hours and 107 instructor pilot hours. He is also a qualified Forward Air Controller (Airborne) (FAC(A)). This...
read moreSécurité Civile EC145 Mountain Rescue Blade Strike
Sécurité Civile EC145 F-ZBPI / Dragon 74 Mountain Rescue Blade Strike near Annecy During a mountain rescue SAR mission on 17 June 2019 Sécurité Civile Airbus Helicopters EC145 (BK117C2) F-ZBPI, call sign DRAGON 74, based at Annecy Haute-Savoie Mont-Blanc airport (BH74), suffered a main rotor blade strike in the French Alps. The Accident Flight Investigators of the BEA-Etat (BEA-E) explain in their safety investigation report, issued on 7 September 2020 in French only, that the tasking was to rescue two hikers who had got into difficulties in the Goulet du Pontet (Haute-Savoie), at c 4,900 ft amsl. This was their fourth mission since 0900 that morning, typical for the unit in the summer. The crew consisted of 4, a pilot, hoist operator and two mountain rescuers (one a first aid trained Gendarme and the other a firefighter). They were tasked by the local fire and rescue operational centre (known as CODIS) at 1848. The helicopter departed at 1859, arriving on-scene just 7 minutes later. The location was “well known to the crew” and the weather was “very good…with clear visibility over 10 kilometres” and a “weak north westerly wind of 5 to 10 kt, gusting 15 kt”. “…the crew agreed on the choice of the skid support procedure”. This involved resting a skid on the ground to disembark / embark personnel (example video). They had used both this and hoisting during the three earlier missions that day. This technique is quicker and requires less power and so is preferred when it is practical. The pilot spotted a grassy area suitable for maneuvering, upstream of the hikers. DRAGON 74 performs a first pad support and disembarks the two rescuers. As the helicopter takes off again, the hikers rush towards the rescuers who secure them. By radio, the lead mountain rescuer calls DRAGON 74… Less than a minute passes between the two approaches. When DRAGON 74 arrived for the second skid support, the crew heard a noise from the blades of the main rotor. The pilot interrupts his approach, immediately deviates and, while hovering, checks the helicopter parameters. Not noting any particular vibration and the parameters being compliant, the pilot decided to continue the mission and recover the rescuers as well as the hikers by hoist. After having landed on a field of Montmin, rotor turning, and put down the hikers, DRAGON 74 returns to its base without additional verification. During the post-flight inspection, the crew noticed that the main rotor of the helicopter was damaged. The BEA-E Safety Investigation BEA-E comment that the unit did not have a conventional Operations Manual, but a series of overlapping instructions and other documents, which don’t address skid support rescues. When examined, traces of vegetation were found on all four blades of the main rotor, with the yellow blade suffering a penetration at the leading edge. The site of the incident was located south of the Pointe de la Beccaz, in the Goulet du Pontet, on a grassy area sloping 45° on the side of the mountain. The area is about fifteen meters long. Two shrubs over two meters are found on the upper part of the area. Numerous branches were found damaged but none were actually cut. The BEA-E examined recorded data from the aircraft: At the time of the collision, the rotor rpm remained constant around 102%. The only variation in speed, less than 1%, is attributable to the engine / rotor control and was visible during the entire part of the hover. The aircraft was subject to Airbus’...
read moreDash 8 Q400 Control Anomalies: 1 Worn Cable and 1 Mystery
Dash 8 Q400 Control Anomalies: 1 Worn Cable and 1 Mystery On 14 November 2019 Flybe Bombardier Dash 8 Q400 G-FLBE suffered a flight control anomaly and diverted to Exeter. The UK Air Accidents Investigation Branch (AAIB) explain in their safety investigation report (issued 15 October 2020) that shortly after takeoff in a strong crosswind from Newquay, the flight crew noticed that both control columns / control wheel (referred to by AAIB as ‘handwheels’) were offset to the right by up to 40° in order to maintain wings level flight. The crew consulted the Quick Reference Handbook (QRH) but found no checklists that they considered helpful. After an unfruitful radio discussion to gain engineering advice, the crew made the decision to divert to Exeter, where the aircraft landed safely, 41 minutes after take off. The AAIB Safety Investigation The QRH did contain a checklist for ‘Roll Control Malfunction – Aircraft rolls with no Control Wheel Input’ (reproduced below). The AAIB comment that: …the pilots did not recognise the relevance of this checklist, possibly because the AP was engaged and would have automatically countered the uncommanded roll to the left. The checklist commences with several actions, including one, relevant to this case, to increase airspeed. The manufacturer advised that the intent of increasing airspeed is to improve roll authority with the remaining controls. Unhelpfully there is no guidance on how much airspeed should be increased. The second part of the checklist addresses the landing considerations and directs the crew to land at an airport with minimal crosswind and suggests the use of either Flap 15 or 35. However, the manufacturer stated that any allowable landing Flap setting would be acceptable and the aircraft was cleared to land with Flap 10, 15 or 35; it was only the operator’s version of the QRH that restricted the choice of Flap. The manufacturer advised that consideration of minimal crosswind was a generic expression that they used in a number of checklists and the intention was to remind pilots to consider the ‘retained lateral control authority for landing’. Therefore, commanders should select an airfield which has the lowest crosswind component. The checklist also directs the pilots to use the non-normal Landing Distance Required (LDR) table in the QRH. As the pilots felt that the QRH was not relevant, they did not complete these actions and instead used the normal VREF and landing distance. The runway at Exeter was sufficiently long for the increased LDR. The aircraft was subsequently inspected at Exeter, which… …revealed that the lower left aileron cable broke just outboard of the engine where it passed over a pulley to accommodate a change in the wing dihedral. There was no other damage to the aircraft. When the handwheels were rotated through their full range of movement, the right aileron operated normally, whereas the left aileron remained in the fully up position. When the outboard section of the broken cable was pulled, the left aileron moved towards the neutral position and when released returned to the up position. The AAIB explain that… On the ground, if the lower aileron cable breaks, the tension in the upper cable will cause the aileron to deflect upwards, and conversely, if the upper cable breaks the aileron will deflect downwards. Following the failure of a cable in-flight, the position of the aileron surface would be dependent on the aerodynamic loads (speed of...
read moreHawaiian Air Tour EC130T2 Hard Landing after Power Loss (Part 2 – Survivability)
Hawaiian Air Tour EC130T2 Hard Landing after Power Loss – Part 2: Survivability (Blue Hawaiian N11VQ Kauai) On 17 January 2016 Airbus Helicopters EC130T2 N11VQ, operated by Blue Hawaiian Helicopters (an Air Methods subsidiary), crashed near Hanalei, Kauai, Hawaii during a Part 135 air tour flight. The pilot and six passengers were all seriously injured. In this, the second of two articles, we look at the survivability issues in more detail. The Accident Flight The US National Transportation Safety Board (NTSB) explain in their safety investigation report (issued 25 August 2020): The pilot reported that, about 25 minutes after departure for the sightseeing flight, the helicopter was about 1/4-mile offshore NW of the Honopu Sea Arch between 1,300 ft and 1,400 ft mean sea level (msl) when he heard the low rotor rpm aural warning horn. The first indication of an inflight loss of power was an uncommanded right yaw that occurred at 14:31:31. The pilot entered an autorotation, initiated a 20° right turn turned toward shore and made a distress call. After about 11 seconds, the coastline became discernable and revealed a rocky, unsuitable landing area. At 14:32:08, the helicopter had entered a 45° right bank, altitude was 275 ft, airspeed was zero, and the helicopter was maneuvering toward a sandy beach area. About 3 seconds later, the LIMIT (servo limit) light illuminated, the helicopter entered a near-level pitch attitude, airspeed was near zero, and rotor speed was around 200 rpm. Initial ground impact was at 14:32:13 and the rotorcraft was at rest at 14:32:15. All occupants were seriously injured. NTSB Probable Cause Part 1 of our article looked at the cause of the power loss. The NTSB Probable Cause was: The fatigue failure of the engine fuel pipe as a result of vibration caused by a worn starter-generator front bearing support, which excited the fuel pipe and caused it to oscillate at a resonant frequency, and a subsequent loss of engine power due to fuel starvation. However, the NTSB go on to note that: Contributing to the severity of passenger injuries was the improper positioning of the passengers’ seat belts. They however do not give credit to the design of the EC130 which allowed all the occupants to at least survive a very high g impact. NTSB Safety Investigation: Survivability When the wreckage was examined: The tail skid was bent up into bottom of the fenestron and the bottom of the fairing displayed a 20-inch crack in the longitudinal direction. The tail boom was symmetrically buckled on the left and right sides at the intermediate structure attach point and had significant buckling at the bottom. The rear fenestron drive shaft support bracket displayed a slight buckle. The engine deck was slightly buckled aft of the rear engine support. Plastic deformation of the engine support in the aft direction was observed. The right transmission bay, transmission support rod, and lower rod end rivets had sheared along the support tube axis. The main gear box (MGB) right support rod was deflected 24 mm at the largest point (mid span). The right cargo bay had no noticeable buckling of the X-wall. The cockpit center console’s forward upper mount plate was buckled on the right side. The left MGB support rod rivet heads were sheared. The left cargo bay displayed buckling of the X-wall at the lower aft corner. The left firewall had buckled along the lower edge....
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