A Saab 2000 Descended 900 ft Too Low on Approach to Billund
A Saab 2000 Descended 900 ft Too Low on Approach to Billund (Darwin Airlines HB-IZW) On 10 December 2015 Saab 2000 HB-IZW of Darwin Airline (branded Etihad Regional but operated for on behalf of Air Berlin), that had earlier departed from Berlin Tegel, Germany, suffered a serious incident on approach to Billund, Denmark. During this approach, the aircraft descended steeply and below the minimum safe altitude prompting a Terrain Avoidance and Warning System (TAWS) warning. The aircraft diverted back to Berlin and landed safely. History of the Accident Flight The Swiss Safety Investigation Board (SUST) explain in their safety investigation report that the Aircraft Commander had 8022 flying hours experience (but only 170 on type) and the co-pilot had 12100 hours experience (1022 on type). The weather in Billund that afternoon was overcast with a 600ft cloud base. After an uneventful cruise flight, the pilots noticed problems with the glideslope indication during the approach to Billund Airport. At an altitude of 800 ft above ground and 250 ft below the minimum altitude stipulated for this position, the pilot flying [PF – the Aircraft Commander] initiated a go-around. Because of the problems with the glideslope indication, the pilots decided to perform a non-precision approach using the localiser for the second approach. The safety investigators report that: During the [second] descent, the PM [Pilot Monitoring] tried to calculate the reference altitude for the correct glide path for a specified distance. He was not able to calculate this because he wanted to use the DME distance but could not find any DME information on the approach chart. He did not communicate that he was unable to come to a result and hence was not monitoring the vertical flight profile. When the aircraft was at a DME distance of 5.5 NM and an altitude of 1240 ft AMSL, the auto-callout ‘one thousand’ sounded, meaning that the aircraft was 1000 ft above ground. According to their statements, the crew noticed at this time that something was not right, but they did not realise what was wrong. 19 seconds later, the enhanced ground proximity warning system (EGPWS [i.e. a Honeywell TAWS]) sounded for one second with a glideslope warning. The investigators comment that: According to their statements, the crew was convinced that something was wrong when the auto-callout ‘five hundred’ sounded another 12 seconds later. 7 seconds later, at an altitude of 757 ft AMSL or 404 ft AGL, the PF decided to initiate a go-around. At approximately the same time, the EGPWS ‘terrain ahead, pull up’ warning sounded. The PF flew the normal go-around procedure and, one second after the EGPWS warning, the go-around mode was active. The lowest altitude during the go-around was 700 ft AMSL or 346 ft AGL. After they had completed an analysis of the problem, the crew decided to return to Berlin…as the weather in Berlin allowed for a visual approach. The remainder of the flight was uneventful. The investigators say that after the flight: After…the crew concerned made a telephone call to the company to inform them that they had to execute a go-around during the approach to Billund Airport due to receiving a false warning from the EGPWS. The aviation company’s safety manager only realised that the incident had been a serious incident during the routine flight data monitoring (FDM) of the day’s operations and reported...
read moreNTSB on LA A109S Rooftop Hospital Helipad Landing Accident
NTSB on Los Angeles A109S Rooftop Hospital Helipad Landing Accident (N109EX of Helinet Aviation Services / Prime Healthcare at USC Kerk) The US National Transportation Safety Board (NTSB) have published their preliminary report on Leonardo Helicopters AW109S N109EX of Helinet Aviation Services which crashed onto the University of Southern California (USC) Keck Medical Center (USC Keck) rooftop helipad in Los Angeles, California on 6 November 2020. UPDATE 28 January 2023: NTSB have now published further factual information (see below) that puts attention on the tail rotor and past inspections. The helicopter was making a Part 135 helicopter air ambulance flight, with a donor heart for a transplant operation aboard. The pilot suffered minor injuries and the two passengers were uninjured. The Los Angeles Fire Department (LAFD) retrieved the organ from the wreckage and the hospital says “the heart was successfully transplanted following the crash, and the transplant recipient is recovering well”. The Accident The US National Transportation Safety Board (NTSB) explain in their preliminary report that: The pilot reported that he established the helicopter in a steep approach, to land on the rooftop helipad of a multi-story medical building [approaching in a northerly direction over Hazard Park according to videos of the accident]. The pilot had offset his heading to the left to gain greater visibility to the landing zone. He observed the absence of any wind indication from the windsock and no movement on nearby trees. When the helicopter had decelerated to about 45 knots, he increased the engine and rotor RPM to 102%. About 40 feet above the helipad, the pilot noticed a slight yaw to the right that continued despite full left pedal application. He thought to fly away from the helipad when the helicopter aligned in the direction he just approached from. As the helicopter rotated to about 90° from his approach heading, it suddenly and very violently made a dramatic increase in right yaw. Realizing the helicopter was going to be uncontrollable, the pilot “dumped the collective” and tried to stay over the helipad. He stated that after the helicopter struck the helipad, it rolled left and continued spinning on its side, and eventually came to a stop. The pilot shut down the engines and all three occupants exited unassisted. The NTSB say that: A review of a witness video, (See figure 1), taken from an adjacent building, revealed the helicopter approached the rooftop helipad while slowly rotating clockwise about the vertical axis. The helicopter stopped descending and rotated 360°. The helicopter then descended while rotating an additional 180° and rolled to the left before impacting the helipad. The main rotor blades contacted the helipad, followed by the left main landing gear and the fuselage. The helicopter descended out of view of the camera. The helicopter came to rest on its left side, on the helipad. The four composite blades of the main rotor system fragmented and separated, spreading debris throughout the rooftop and down to the ground. The tail rotor and 90° gearbox separated and were found on the rooftop. The left main landing gear separated and remained near the attachment points of the fuselage. UPDATE 28 January 2023: NTSB Safety Investigation Factual Report: Focus on Tail Rotor Ring Nut NTSB investigators have revealed that the tail rotor assembly rotating control ring nut was separated from the thrust sleeve assembly. No other pre-impact defects were found. Examination of the tail rotor assembly and 90° gearbox by the NTSB...
read moreAir Ambulance A109S Spatial Disorientation in Night IMC
Air Ambulance Helicopter Spatial Disorientation in Night IMC (North Memorial Healthcare Leonardo A109S N11NM, Minnesota) On 28 June 2019, at about 0040 Local Time Leonardo Helicopters AW109S N11NM, an air ambulance operated by North Memorial Healthcare, was destroyed at Brainerd Lakes Regional Airport (BRD), Minnesota. The pilot and flight nurse died at the scene. The flight paramedic was seriously injured. The helicopter had been approaching the airport in dark night instrument meteorological conditions (IMC) after delivering a patient to the North Memorial Medical Centre and was just commencing a missed approach. This was the operator’s second night A109S accident in less than three years. The previous one, non-fatal, involving N91NM on 17 September 2016 was discussed in this Aerossurance article: HEMS A109S Night Loss of Control Inflight, issued on 29 September 2018. That also involved a missed approach and NTSB determined in the first accident that “the pilot’s excessive cyclic input…resulted in a loss of control and spiralling descent into terrain”. The Safety Investigation The US National Transportation Safety Board (NTSB) explain in their safety investigation report (issued in November 2020) that N11NM was… …equipped with a 2-axis autopilot for lateral (roll) and longitudinal (pitch) control. The autopilot provided for limited yaw dampening, but no yaw control. Minimum airspeed to comply with IFR handling quality requirements for the helicopter [Vmini] was 55 knots. The pilot had 3376 hours total, 533 on type and 2294 as Pilot In Command. The pilot’s most recent Part 135 competency/proficiency check occurred on March 12, 2019. During the 90 days before the accident, the pilot logged 27 landings at night, 16 instrument approaches, 1 flight hour of actual instrument time, and 57 hours of simulated instrument time. The pilot’s total actual instrument time flown was 41 hours. BRD was located in a rural area with few ground lights, and there was no moon illumination at the time of the accident. Airport personnel stated that several lakes near BRD would often generate patchy fog and visibility could vary significantly at different locations on the airport. Another pilot working for the operator told the NTSB: I’ve experienced some weird things at Brainerd… I’ve seen it in both directions, where it’s worse than it says it is, and I’ve seen it where it’s way better than it says it is. History of the Accident Flight The flight was returning to BRD after delivering a patient to North Memorial Heliport (MY77), Robbinsdale, Minnesota. An onboard Appareo Vision 1000 device recorded flight data, cockpit imagery, and audio of the flight. The helicopter departed MY77 at 2348, and the pilot received an instrument flight rules [IFR] clearance from air traffic control (ATC) to climb to 6,000 ft mean sea level (msl) and fly direct to BRD. At 2356, while holding an iPad, the pilot stated on intercom to the paramedic and/or flight nurse that visibility at BRD was “1 mile, looks good.” The pilot requested the instrument landing system runway 23 (ILS RWY 23) approach and informed the controller that he had obtained the current weather at BRD. At 0028, the pilot selected the BRD automated surface observing system (ASOS) frequency. The ASOS transmission included a ceiling of 200 ft above ground level (agl) and 1/4-mile visibility with fog. The controller cleared the helicopter for the ILS RWY 23 approach. Shortly thereafter, the ASOS transmitted weather included 1/2-mile visibility with haze, and the pilot stated “awesome, 1/2 we’re legal” on the intercom. The pilot subsequently activated the runway lights. At 0034:35, the helicopter began a descent on the ILS glideslope with the autopilot coupled. About 5 seconds...
read moreAlaskan AS350B3e Accident: Botched Autorotation Practice?
Alaskan Airbus AS350B3e Accident: Botched Autorotation Practice? (N907PL) On 28 September 2018 a private Airbus Helicopters AS350B3e (H125) N907PL was destroyed in an accident in Glacier Bay National Park, near Lituya Bay, about 60 miles NW of Gustavus, Alaska. One person died, 2 remain missing presumed dead and one was seriously injured. The US National Transportation Safety Board (NTSB) explain in their safety investigation report that: The private pilot [aged 42, 1,129 flying hours total, 26 on type and president of Anchorage’s Davis Constructors and Engineers] had just purchased the helicopter… He had done a AS350B3e factory course in Texas with 3 hours of flight time and 1 hour of simulator time. He had then done 18.3 hours of flying an AS350B2 in Alaska, and another 6 hours on the AS350B3e in Texas, before embarking on the delivery flight from Texas to Alaska. The trip began on September 25, 2018, and included more than 30 stops for sightseeing, fuel, and rest. The left seat safety pilot [aged 53, 15,350 flying hours total, 4350 on type, who had flown with the owner for 11.4 hours in an AS350B2 previously] was onboard for insurance coverage purposes and was acting as a safety pilot. The safety pilot was the owner, director of operations, and chief pilot for two different commercial helicopter operators in Alaska that operated several AS350B2 model helicopters. The right seat pilot-in-command [the owner] planned to drop off the safety pilot in Wasilla, Alaska, then proceed to Anchorage with the [two] passengers [the young sons of the pilot owner]. N907PL was equipped with a Genesys Aerosystems HeliSAS autopilot and stability augmentation system. The NTSB comment that in an interview after the accident the survivor, a 14-year-old boy, stated that… …the safety pilot did not seem recently familiar with the B3e model and the options that were installed on the accident helicopter. The safety pilot asked a lot of questions about the B3e, and the [owner] pilot appeared more familiar with the helicopter systems than the safety pilot. This may have course have been the safety pilot checking the owner pilot’s understanding. Although not mentioned by the NTSB, the survivor also commented that both pilots were aware of a past accident where an object in the cabin caught on flying controls and were very alert to that hazard. During this trip the helicopter departed Juneau, Alaska that morning bound for Yakutat, Alaska. It proceeded west over the mountains st 3000-4000 ft AMSL, then north-west along the coast at about 500 to 700 ft AMSL. Video from the cockpit image recorder [an Appareo Vision 1000] indicated that the pilot, seated in the right seat, was manipulating the flight controls from takeoff until the accident occurred [there is no mention of the NTSB of any analysis of the audio data recorded]. The surviving passenger stated that, while en route, the pilot indicated that they would be landing on a beach in order to stretch their legs. The recovered data showed the helicopter flying about 500 to 700 ft over water when the pilots began conversing and pointing toward the shore. The safety pilot, whose hands were on his lap, then raised his right hand in a manner that appeared that he was guarding the cyclic control in anticipation that his assistance or intervention might be required. Shortly thereafter, the pilot twisted the collective twist grip throttle from FLIGHT to IDLE; data from the engine data recorder (EDR)...
read moreAOA Anomalies on Successive B737-800 Flights
AOA Anomalies on Successive Transavia Boeing 737-800 Flights (F-GZHO) Transavia France Boeing 737-800 F-GZHO suffered Angle of Attack (AOA) anomalies and alerts during take off from Norwich, UK on 7 February 2018 and then on 8 February 2018 after take off from Paris Orly, France. The French Bureau d’Enquêtes et d’Analyses pour la Sécurité de l’Aviation Civile (the BEA) explain in their safety investigation report, issued on 16 November 2020, that the first flight was a ferry flight after a base maintenance C-Check at KLM UK Engineering with just 3 persons on board and then the second a revenue flight with 180 persons on board. Aircraft Systems Context BEA explain that: IAS DISAGREE, AOA DISAGREE and ALT DISAGREE messages are generated by the DEU [Display Electronics Units] 1 and 2 based on the data provided by the two ADIRUs [Air Data Inertial Reference Units]. These messages are displayed in amber on the PFD without an audio warning. The conditions for the activation…are the following: The IAS DISAGREE message is displayed on the two PFDs when there is a difference of more than 5 kt for at least 5 seconds between the left and right indicated airspeed values. The AOA DISAGREE message is displayed on the two PFDs when there is a difference of more than 10° for at least ten seconds between the angle of attack values measured by the left and right sensors. The ALT DISAGREE message is displayed on the two PFDs when there is a difference of more than 200 ft for at least 5 seconds between the left and right altitude values. The 737 is equipped with two AOA sensors installed on the forward fuselage…. The external part of the sensors consists of a heated vane which positions itself in the air flow bed. The rotary movement of each sensor is transmitted to two electric resolvers, located in the body of the sensor, by means of internal gears. The resolvers transform the rotary movement into an electrical voltage value which is proportional to the angle of attack. Within each sensor, resolver 1 sends its electrical data to the SMYDC [Stall Management Yaw Damper Computer] and resolver 2 to the ADIRU which generates the air and inertial data of the aeroplane. Resolvers 1 and 2 are mechanically linked by a gear. Thus, when the AOA sensor functions nominally, the angular positions of the two resolvers change at the same rate. An angle of attack measurement error thus affects the indicated airspeed and altitude displayed on the PFD on the side of the erroneous measurement. …in addition to the indicated airspeed and altitude display errors, the various computers situated on the same side as a malfunctioning AOA sensor receive false input data. These dysfunctions may result in an increased work load for the crew along with difficulties in controlling the aeroplane. During a C-check one… …inspection required the two AOA sensors to be manually turned by 30°. The technicians who had carried out this operation had not noticed any anomaly. Flight on 7 February 2018 The aircraft took off at 18:40 in night Visual Metrological Conditions (VMC). The captain was Pilot Flying (PF). …at roughly the moment when the captain carried out the rotation, the IAS DISAGREE alert message appeared on both PFDs. The crew called out the appearance of the alert and quickly saw that the right PFD [Primary...
read moreShort Sling Stings Speedy Squirrel: Tail Rotor Strike Fire-Fighting in Réunion
Short Sling Stings Speedy Squirrel: Tail Rotor Strike Fire-Fighting in Réunion (Hélilagon Airbus AS350B3e / H125 F-OFML) with Video On 24 January 2019 Airbus Helicopters AS350B3e (H125) Squirrel F-OFML of Hélilagon suffered a tail rotor failure during fire-fighting with an underslung bucket at Grand-Brûlé, Sainte-Roseon on the Indian Ocean island of Réunion. The French Bureau d’Enquêtes et d’Analyses pour la Sécurité de l’Aviation Civile (the BEA) explain in their safety investigation report (issued only in French) that the pilot (who had 10,129 hours of flying experience and 4,198 on type) had been flying for four days fighting fires on the eastern side of the Piton de la Fournaise volcano. This was by both by direct water drop and replenishing temporary reservoirs set up by ground fire-fighters using pumps and hoses. The helicopter had an underslung 820 litre Type 1821 Bambi Bucket on a short 5 m sling (so the bottom of the bucket was c 9.7 m below the helicopter in the hover) to do both tasks. Having dropped water on the main front of the fire at 2,200 ft AMSL (location 2 the graphic below), the helicopter was returning to collect more water from a point about 2 nm away, on the lower slopes of the volcano at 385 ft AMSL (location 1 below). Wind was north-easterly, gusting 30 knots. During that leg while descending through at 930 ft AMSL at 13:48:17 (location 3), the pilot heard a high-frequency noise at the same time as feeling a slight jerk to the left. The pilot then perceived a loss of effectiveness of the rudder pedals. After a MAYDAY call, the pilot continued flying with the intention of finding a suitable area for an emergency landing. This part of the flight was captured on the early part of the VIDEO. The pilot was not able to find a location suitable for a run on landing. When airspeed was reduced, the helicopter started to rotate around its yaw axis and made two and a half turns before a hard landing at 13:52:45 (in location 4 at 315 ft AMSL) on a lava flow from 2002, near the coast road. The helicopter was shutdown. On egress the pilot discovered the cables of the fire-fighting bucket were entangled with the tail rotor and the tail rotor blades were broken at 3/4 length. The right skid was broken in several places and there was impact damage from the underslung load on the tailboom. A local news report contained close-up images. Closer examination revealed that the Tail Gear Box (TGB) casing had fractured around its circumference. The BEA determined this was due to overload when the blades struck the underslung load. The BEA observe that flight and wind parameters derived from the two independent onboard recording systems (an Appareo Vision 1000 and a Helisafe system) “show that the helicopter was operating in a very turbulent air mass”. This is likely due to be a combination of the wind and the Volcano topology, supplemented by heat from the fire. When the underslung load hit the tail rotor the helicopter was flying at an indicated speed of 97 kt, with a rate of descent of 1,230 ft/min in a “particularly turbulent environment”. The BEA note that the manufacturer’s manual for the fire-fighting bucket can only be complied with if the bucket is connected directly to the cargo hook (with no sling) or by using a sling of at least 15 m. The manual also states airspeed with the bucket fitted should not...
read moreEmbraer ERJ-190 EWIS Production Quality a Factor in Fire
Embraer ERJ-190 EWIS Production Quality a Factor in Fire (Azul PR-AUO) On 21 February 2017 Azul Linhas Aéreas Embraer ERJ-195AR (ERJ-190-200 IGW) PR-AUO was at approximately 14,000ft on descent Vitória, Espirito Santo, Brazil. A short circuit occurred with overheating and sparks inside the cabin near seat 03A. A cabin crewmember discharged two fire extinguishers after using a fire axe to get better access. The pilot declared an emergency and a safe landing was accomplished without any injuries. The Brazilian accident investigation agency CENIPA explain in their safety investigation report (dated 2 October 2020 and only available in Portuguese) that the aircraft suffered damage to the cabin trim sidewall. Between the sidewall and the aircraft’s external skin, as well as structure there is a thermal / acoustic barrier, wiring and an electromagnetic protection blanket. Upon removal of the sidewall the source of the fire was identified as being related to EWIS (Electrical Wiring Interconnection Systems). Several wires had melted, characteristic of a short circuit. The affected wiring was PN 191-32836-401. The damage was located near the P1143 electrical connector. The affected conductors were part of two different circuits. One of these circuits connected the AC BUS to the Left Integrated Control Center (LICC) and the direct current (DC) Windshield Heating Control Unit 2. The other circuit connected the AC GND SVC, located at LICC, to the Secondary Power Distribution Assembly (SPDA1), for the control and monitoring of energy for electrical system components. The associated circuit breakers (CBs) had both tripped and it is that, rather than the fire-fighting, which CENIPA believe resulted in the fire ceasing. The CBs were tested and found to meet their specification. When wiring adjacent to seat 3D, on the opposite side of the cabin, was examined there were signs of chafing between the wiring and the electromagnetic protection blanket. Investigators then examined PR-AUM and PR-AUP, two aircraft with serial numbers close to that of the PR-AUO. Further chafing was observed on both those aircraft. While the Maintenance Review Board (MRB) for the type had identified the need for a periodic inspection of the general condition of the wiring, this was scheduled for every 36,000 flying hours. PR-AUO aircraft had flown only 4,047 hours. PR-AUP and PR-AUM also had less than 5,000 hours. A check of maintenance records for these aircraft confirmed the wiring harnesses had not been disturbed in-service. The investigators confirmed that: …contact between the sidewall and the wiring allowed relative movement and consequent friction between the parts. The friction resulted in loss of material from the surfaces in contact. Due to its physical characteristics, the process of material loss in the wiring was more accentuated and consumed the insulating material of the cable, allowing the exposure of the conductive wire. This scenario favored the occurrence of the short circuit. The short circuit between the conductors led to the collapse of the systems fed by these wires. However, the affected systems had specific redundancies and protections, such as CBs… CENIPA verified that there were appropriate production instructions for wiring installation but that production quality deviations had occurred on the aircraft examined. The investigators expressed concern on the use of the fire axe: The place where the hatchet was used in the occurrence was an area where several power cables passed from the aircraft systems. An eventual cut of one of these harnesses could result in a larger occurrence. ANAC regulations, as well as the company’s and manufacturer’s flight attendant training manuals, did not specify in detail how to use this equipment, notably...
read moreHEMS EC135T1 CFIT During Mountain Take Off in Poor Visibility
HEMS EC135T1 CFIT During Mountain Take Off in Poor Visibility (Air Glaciers EC135T1 HB-ZIR) On 24 March 2018 Air Glaciers HEMS Airbus Helicopters EC135T1 HB-ZIR crashed on its third flight of the day in connection with the rescue of an avalanche victim, on the Col du Grand St-Bernard in Switzerland. The Swiss Safety Investigation Board (SUST) explain in their safety investigation report (issued 28 September 2020 in German) that an avalanche search dog, its handler and a mountain guide were unloaded in car park in Grand St-Bernard at c 8000 ft AMSL. The helicopter was then to make a return flight to Sion. The pilot and a Technical Crew Member (TCM), who was also a paramedic, were on board. The pilot was 55 and had 13,030 flying hours experience in total, 575 on type. Visibility was poor with low-lying clouds with a cloud base that was only 100 ft above ground at times. The wind was blowing from 280 degrees at 15 kt, gusting 20 kt. The pilot choose a traffic sign which protruded from the snow c 140 m away as a visual reference. HB-ZIR took off shortly after 09:30 and the pilot checked various parameters while hovering. After all technical parameters had been checked by the pilot, the helicopter flew in the direction of the reference point in slow forward flight…estimated to be the speed of a person running. Shortly afterwards, the TCM noticed that the machine was approaching the ground. He then called to the pilot, who was focused on his reference point, to pull up. But before he could react HB-ZIR collided with the ground and overturned in the snow. The main rotor cut through the tail boom and three of the four rotor blades separated from the main rotor head. The helicopter came to a standstill on its left-hand side, facing the direction of flight, on rising terrain. Both occupants were uninjured. SUST Conclusions There are no indications of technical restrictions that could have caused or influenced the accident. …the pilot did not recognize the approach of the helicopter to the terrain during take-off over a blanket of snow with no reference to the terrain. The TCM’s warning came too late to act. The gusty tailwind contributed to a descent that was more pronounced than anticipated by the crew. Safety Resources Sécurité Civile EC145 Mountain Rescue Blade Strike Hanging on the Telephone… HEMS Wirestrike Air Ambulance Helicopter Downed by Fencing FOD Ambulance / Air Ambulance Collision Fatal Fatigue: US Night Air Ambulance Helicopter LOC-I Accident Italian HEMS AW139 Inadvertent IMC Accident Norwegian HEMS Landing Wirestrike HEMS A109S Night Loss of Control Inflight HEMS S-76C Night Approach LOC-I Incident US Fatal Night HEMS Accident: Self-Induced Pressure & Inadequate Oversight HEMS Black Hole Accident: “Organisational, Regulatory and Oversight Deficiencies” Taiwan NASC UH-60M Night Medevac Helicopter Take Off Accident EC130B4 Destroyed After Ice Ingestion – Engine Intake Left Uncovered Dim, Negative Transfer Double Flameout EC135P2 Spatial Disorientation Accident Fish Spotting Helicopter Strikes Glassy Sea Austrian Police EC135P2+ Impacted Glassy Lake EC135P2+ Loss of NR Control During N2 Adjustment Flight US HEMS EC135P1 Dual Engine Failure: 7 July 2018 Misassembled Anti-Torque Pedals Cause EC135P1 Accident AAIB Report on Glasgow Police EC135T2+ Clutha Helicopter Accident Maintenance Misdiagnosis Precursor to EC135T2 Tail Rotor Control Failure B206B Hit by Truck in Forced Landing after 16 Months of Operation with Unairworthy Engine Tragic Texan B206B3 CFIT in Dark Night VMC Deadly Dusk Air Ambulance Bird Strike UPDATE 4 December 2020: Air Ambulance A109S Spatial Disorientation...
read moreKing 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...
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