News & Comment

HEMS A109S Night Loss of Control Inflight: Excessive Cyclic Input in Missed Approach

Posted by on 9:08 am in Accidents & Incidents, FDM / Data Recorders, Helicopters, Human Factors / Performance, Safety Management, Special Mission Aircraft

HEMS A109S Night Loss of Control Inflight (LOC-I): Excessive Cyclic Input in Missed Approach (North Memorial, N91NM, Minnesota) On 17 September 2016 a Leonardo AW109S Grand air ambulance helicopter, N91NM, operated by North Memorial Air Care, crashed near Chandler Field Airport (AXN), Alexandria, Minnesota. The pilot and both medical personnel on board were seriously injured and the helicopter was destroyed in yet another night HEMS accident in the US. The Accident Flight The helicopter was positioning from Brainerd Lakes Regional Airport (BRD), at night under instrument flight rules (IFR), departing at 01:37 local time, for the Douglas County Hospital helipad via AXN were they were to pick up a patient. According to the US National Transportation Safety Board (NTSB) safety investigation report: During the instrument approach to [AXN] the weather conditions deteriorated. The pilot was using the helicopter’s autopilot to fly the GPS approach to the airport, and the pilot and the medical crew reported normal helicopter operations. Upon reaching the GPS approach minimum descent altitude, the pilot was unable to see the airport and executed a go-around. The pilot reported that, after initiating the go-around, he attempted to counteract, with right cyclic input, an uncommanded sharp left 45° bank . Recorded flight data revealed that the helicopter climbed and made a progressive right bank that reached 50°. The helicopter descended as the right bank continued, and the airspeed increased until the helicopter impacted treetops. The helicopter then impacted terrain on it’s right side and came to rest near a group of trees. The accident site was located in a residential area surrounded by trees about 1,000 yards northwest of the approach end of AXN’s runway 22. The debris path was about 130 yards long and began with lopped tree tops (95 to 100 ft tall) and ended about 30 yards beyond the main wreckage.  The NTSB Safety Investigation The NTSB confirmed there were no defects with the aircraft or its systems.  The helicopter did have a GPS roll steering modification but the NTSB determined “this could not compromise the flight director and autopilot functionalities to the point of upsetting the helicopter attitudes or moving beyond the systems limiters”. Recorded helicopter, engine, and flight track data were analyzed and used to conduct flight simulations. The simulations revealed that the helicopter was operated within the prescribed limits; no evidence of an uncommanded 45° left bank was found. The helicopter performed a constant right climbing turn with decreasing airspeed followed by a progressive right bank with the airspeed and descent rate increasing. In order to recover, the simulations required large collective inputs and a steep right bank; such maneuvers are difficult when performed in night conditions with no visual references, although less demanding in day conditions with clear visual references. The data are indicative of a descending accelerated spiral, likely precipitated by the pilot inputting excessive right cyclic control during the missed approach go-around maneuver, which resulted in a loss of control. The pilot was the Director of Operations for North Memorial Air Care and he exceeded the regulatory currency requirements for night flying. He had a ‘normal night sleep the night before’, but this is not detailed, and a nap for 2 hours during the afternoon.  He had only gone to sleep shortly before being called for the accident flight (having been earlier called at 00:30 for another possible flight,...

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Eclipse 500 Landing Gear Production Defect

Posted by on 3:57 pm in Accidents & Incidents, Business Aviation, Fixed Wing, Maintenance / Continuing Airworthiness / CAMOs, Safety Management

Eclipse 500 Landing Gear Production Defect On 11 June 2015, Eclipse Aviation (now part of ONE Aviation) EA500 N508JA, operated by Memly Aviation, experienced left main landing gear (MLG) collapse while taxiing for departure at Sacramento Executive Airport, California. The three persons onboard were uninjured but there was substantial damage to the left wing. The left MLG trunnion (TSN 1,275 hours and  CSN 1,492 cycles) had broken near the rear attachment point and the MLG had penetrated through the wing. The US National Transportation Safety Board (NTSB) explain in their safety investigation report that: Visual examination revealed that the landing gear fractured at the trunnion portion of the landing gear. The smaller separated piece showed a fatigue crack that emanated from the inner wall. The crack itself was from a machining mark. The area outside of the fracture face contained rough features consistent with an overstress separation. The deep machining mark was in a portion of the trunnion where the inner wall tapered inward, and was in a transition region where the wall thickness was increasing in thickness. The assembly contained a metal squeeze-out typical of forging/casting parts. The excess metal squeezed-out of the forged/casting products are moved by machining, which renders them a high stress area. According to the manufacturer, the initiation of the fatigue crack from a step machined inner wall of the trunnion was outside of the design requirements. Eclipse Aerospace, and the landing gear manufacturer, Mecaer Aviation Group, inspected for the presence of the machined steps. The manufacturer indicated that they had a systemic manufacturing defect that potentially effected the entire fleet of EA500 aircraft.  Eclipse Aerospace and Mecaer, issued a mandatory [sic] Service Bulletin to address the issue. Mecaer also communicated with the machine shop responsible for the defect and process changes were put in place to prevent the issue… Other Safety Resources Production Errors on a SAR Helicopter Full Ice Protection System Machining Defect Cause of V2500 Failure Micro FOD: Cessna 208B Grand Caravan Engine Failure & Forced Landing Metro 23 MLG Corrosion Causes Runway Excursion UPDATE 18 November 2020: Embraer ERJ-190 EWIS Production Quality a Factor in Fire UPDATE 17 September 2022: Canadian B212 Crash: A Defective Production Process  Aerossurance has extensive air safety, operations, airworthiness, human factors, aviation regulation and safety analysis experience.  For practical aviation advice you can trust, contact us at: enquiries@aerossurance.com Follow us on LinkedIn and on Twitter @Aerossurance for our latest...

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Torched Tennessee Tour Trip (B206L N16760)

Posted by on 10:34 am in Accidents & Incidents, Helicopters, Maintenance / Continuing Airworthiness / CAMOs, Safety Management

Torched Tennessee Tour Trip (B206L N16760) On 4 April 2016 Bell 206L N16760 suffered an engine power loss and crashed near Pigeon Forge, TN.  The helicopter was operated by Smoky Mountain Helicopters as a Part 91 local air tour flight.  In such cases the operator is approved by the FAA  to conduct air tours within 25 statute miles of the departure airport under Part 91.147, a rather basic requirement with few obligations compared to Part 135 (Air Taxi). There was no distress call.  According to the US National Transportation Safety Board (NTSB) safety investigation: The helicopter initially impacted trees near the top of a ridge at an elevation of about 1,100 ft mean sea level and came to rest in a wooded area near the bottom of the ridge. A post crash fire ensued. The pilot and four passengers were fatally injured: According to the autopsy reports, all five helicopter occupants suffered blunt force injuries, but three of the five died primarily from thermal injuries; one died as a result of combined thermal and blunt force injuries (pilot); and one died as a result of blunt force injuries. Investigation Examination of the engine fuel pump showed that the small splines of its drive shaft… … exhibited evidence of severe damage, with significant portions of the spline teeth missing material. The drive shaft spacer exhibited thermal distress and indentations consistent with contact with the internal splines of the drive gear. Remnant pieces consistent with the retaining clip, which is normally installed on the spline relief on the drive shaft small splines, were not observed during disassembly but were later identified via photographs taken during the examination… The internal splines of the drive gear also exhibited evidence of severe damage, with significant portions of the spline teeth missing material. The disassembled fuel pump was subject to further lab examination: The hardness and material composition of the drive shaft and drive gear met required specifications. Remnant material on the drive shaft and drive gear splines were similar to mineral-oil-based/soap-thickened lubricants. The illustrated parts list for the fuel pump found in the CMM [component maintenance manual] allowed for 11 different drive shaft spacers of different sizing. According to the CMM, measurements taken during assembly of the drive shaft to the pump assembly are used to select proper drive shaft spacer thickness. The drive shaft spacer installed on the accident fuel pump drive shaft was consistent with a P/N 215981-8 spacer, about 0.240 inches thick. According to the original build record from the manufacture of the fuel pump, dated September 1985, a spacer with a thickness of 0.120 inches was originally installed. Records of fuel pump overhaul preceding the last overhaul were not available, and it could not be determined whether other spacer sizes were used throughout the operational history of the accident fuel pump. In addition, it could not be determined whether the drive shaft, drive gear, and driven gear were original to the fuel pump or, if previously replaced, when the replacement occurred. Overhaul personnel said they had seen similar wear “but not to the severity of the wear observed on the drive shaft from the accident fuel pump”. They had seen such wear “about 4 or 5 times” since 2008, and “a lack of lubricant or corrosion was associated with the spline wear”. NTSB Analysis The wear on the splines was likely accelerated due...

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Crossed Cables: Colgan Air B1900D N240CJ Maintenance Error

Posted by on 6:34 pm in Accidents & Incidents, Design & Certification, Fixed Wing, Human Factors / Performance, Maintenance / Continuing Airworthiness / CAMOs, Safety Management

Crossed Cables: Colgan Air B1900D N240CJ Maintenance Error On 26 August 2003, Beechcraft 1900D, N240CJ, operated by Colgan Air (operated for US Airways Express) crashed shortly after take off on a post-maintenance ferry flight from Barnstable Municipal Airport, Hyannis, Massachusetts, to Albany International Airport, New York. The Accident Flight During the takeoff roll, the pitch trim system began to move in the downward direction. The initial movement from 1.5º to 3º nose down was consistent with an electric pitch trim motor input. Four seconds later the pitch trim movement went from 3º to 7º nose down faster than the trim motor could achieve.  The US National Transportation Safety Board (NTSB) explain in their final report that: The digital flight data recorded (DFDR) indicated that shortly after declaring an emergency, the airplane began a left turn while climbing to 1,100 feet.  Engine torque was reduced, and the airplane remained at 1,100 feet while maintaining an airspeed of approximately 207 knots and 30 degrees of left bank for 15 seconds.  The airplane then pitched down to 8 degrees negative (nose down) and the airspeed increased to 218 knots.  The airplane rolled right and left due to control inputs, and the pitch attitude decreased to 30 degrees negative. The crew declared an emergency, reporting runway trim, and attempted to return to the airport.  The investigation showed that the flight crew had manually selected nose up trim settings, but the aircraft trimmed full nose down. The control column force reached 250 pounds but the crew was unable to maintain control and the aircraft impacted the water off Yarmouth, Massachusetts nose first. Both flight crew, the only occupants, were killed. Prior Maintenance The accident aircraft had been brought in for its Detail 6 (D6) check on Saturday 23 August 2003, which commenced at 16:47. The D6 is one a series of 6 zonal checks conducted over 1320 flying hours.   The emphasis of this check is the empennage and aft fuselage, engine borescope inspections, engine mount torque checks, operational checks and flying control cable tension checks. On the following morning the check was interrupted at 08:00 and the remaining work was deferred. Ten revenue flights were then conducted.  At 20:30 on the evening of 24 August 2003 the aircraft was returned for completion of the D6 check which was concluded at 11:00 26 August 2003.  The NTSB explain that: A maintenance technician conducted a free play check of the left and right elevator trim actuators as part of the Detail Six phase check. Both actuators failed the check, and the failure required replacement of the actuators. During the replacement of the actuators, the technician explained in interview with the NTSB that they chose to omit AMM steps (c) of the Elevator Trim Tab Actuator Removal and step (i) of the Elevator Trim Tab Actuator Installation.   Omission of these steps also eliminated 19 referenced AMM steps.  The technician stated that that was how he had been trained to do the task and Colgan explained that this deviation was rationalised because: In the mind of the Colgan mechanics it was thought that they actually performed the R[emoval] & R[e-installation] of the elevator trim tab actuators in a safe manner because they avoided having to disengage or remove major elements of the flight control system, and disrupted a much smaller portion of the airplane. The technician also did not maintain pressure on the elevator trim tab cables (known as blocking), although...

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Inappropriate Autorotation Training: Police AS350

Posted by on 3:44 pm in Accidents & Incidents, Helicopters, Human Factors / Performance, Safety Management, Special Mission Aircraft

Inappropriate Autorotation Training (Placer County Sheriff, AS350B3 N911WL) On 24 October 2015 Airbus Helicopters AS350B3 N911WL of the Placer County Sheriff’s Department landed hard during a practice autorotation near Folsom, California.  The crew of 3 were uninjured but the helicopter was substantially damaged. In their safety investigation report the US National Transportation Safety Board (NTSB) explain that: The purpose of the public helicopter flight was to perform a patrol mission with a tactical flight officer onboard, while the flight instructor also trained the pilot under instruction (PUI), who had recently been hired by the sheriff’s department. The plan was to perform a routine patrol mission to introduce the PUI to the operation of the helicopter’s systems, then practice autorotations, which the PUI had not previously performed in the accident helicopter make and model. After the patrol, they practiced a series of uneventful autorotations over flat areas. They then landed at McClellan Airfield, and serviced the helicopter with about 120 gallons of fuel. After departure, they flew to a peninsula on the northern shore of the Folsom Lake Reservoir with the intention of performing more enhanced autorotation training. The peninsula, which according to the flight instructor was an area for training approved by the department, was normally partially submerged in water but due to drought conditions, was fully exposed. They go on: The flight instructor was flying the helicopter throughout the maneuver; during the power recovery phase of the autorotation, he applied engine power by moving the throttle twist grip from the idle to the flight position as the helicopter passed through 100 ft. The engine did not respond as he expected, and, unable to reach the pinnacle, he maneuvered the helicopter to a forced landing on downsloping terrain. The helicopter landed hard and tipped forward, resulting in substantial damage to the tailboom and aft fuselage structure. Postaccident examination of the engine and airframe did not reveal any anomalies that would have precluded normal operation, and the engine met its nominal performance parameters during a subsequent test run. No anomalies were found with the engine or its controls. The Rotorcraft Flight Manual recommended that autorotation training be conducted within autorotation distance of a suitable running landing area.  The NTSB highlight that the chosen landing area… …was on a pinnacle, about 100 ft from where the helicopter came to rest. The terrain from the top of the pinnacle to the resting location was on a downward slope of about 4°, and the site was at an elevation of about 455 ft above sea level [and so] did not represent a suitable area for such practice. The site was about 2 miles across the lake from the City of Folsom, however, the closest access via automobile from Folsom would have required a drive of about 27 miles on paved and unpaved roads, followed by an off-road drive of about 1 mile.  Therefore, the chosen location placed the crew in additional danger should a more serious accident have occurred. In fact, almost 4 months before this accident, Airbus Helicopters issued Safety Information Notice (SIN) 2896-S-00 (dated 7 July 2015) on simulated engine-off landing (EOL) training: The notice stated, “Current helicopter accident / incident statistics indicate that the greatest exposure to accidents or incidents is during simulated EOL. The purpose of this Safety Information Notice is to raise the level of...

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Investigation into Jet Airways B777 VT-JEK Serious Incident at Heathrow

Posted by on 10:04 am in Accidents & Incidents, Airfields / Heliports / Helidecks, Fixed Wing, Human Factors / Performance, Safety Management

Investigation into Jet Airways B777 VT-JEK Serious Incident at Heathrow On 30 August 2016  Jet Airways Boeing  B777-300 VT-JEK departed from Runway 27L at London Heathrow bound for Mumbai with 231 passengers and 15 crew on board. The aircraft departed from intersection departure S4E rather than using the full length of the runway and radio altimeter data showed the aircraft a height above ground of 16 feet at the end of the runway and at 112 feet at the airport perimeter road. The investigation was delegated by the UK Air Accidents Investigation Branch (UK AAIB) to the Indian Aircraft Accident Investigation Bureau (AAIB).  Their safety investigation report was published on 10 August 2018. History of the Flight At the time taxiway works mean that an aircraft from Terminal 4, on the south side of Heathrow, would have to cross Runway 27L at S4E, then taxi East, in order to access the full length of 27L. Air traffic asked in the aircraft needed the full length, to which the pilot replied “Negative, S4 acceptable”.  The AAIB say that: As the aircraft passed the end of the runway, the three radio altimeters recorded heights above the surface of 16.4 ft, 16.6 ft and 17 ft respectively. Before the flight the co-pilot had done an initial performance calculation with the aircraft’s Electronic Flight Bag (EFB) Onboard Performance Tool (OPT) that showed take-off from S4E would be acceptable.  This was then repeated by both crew members when the actual, higher, take off mass was confirmed.  The Captain however entered departure from the “First 4” (Northern) intersections to 27L not S4E.  The calculations therefore didn’t agree, until the co-pilot also selected the same erroneous intersections as the Captain. The aircraft therefore took off with a lower thrust than needed. Safety Investigation A Boeing analysis for the AAIB found that the takeoff distance required to meet regulatory requirements was 3349 m whereas the takeoff distance available from intersection S4E was 2589 m.  So while the aircraft lifted off, it: Did not meet regulatory requirements for the all-engine, continued takeoff case. Would not have been able to reject the takeoff and stop in the runway remaining following an engine failure just below V1. Would not have been able to continue the takeoff while meeting regulatory requirements following an engine failure just above V1. AAIB note that: From a procedural perspective, there appeared to be no assurance that an incorrect or invalid entry into the OPT made at the departure briefing would be corrected before the performance calculation was made. Company SOPs separated the calculation of aircraft takeoff performance into two discrete procedures without an explicit check that data entered during the first procedure (the departure briefing) was still valid and appropriate during the second (after receipt of the load sheet). The operator confirmed that, after the crew selected FIRST 4 on the OPT, although four performance solutions were available corresponding to the first four intersections, the default output was used to programme the CDU for departure.  The default output provided performance information for a departure from N1 (Runway 27L full length). The operator reviewed its SOPs and concluded that they did not trap data input errors e.g. using the incorrect runway intersection or environmental conditions, or selecting the incorrect thrust de-rate. It issued SOP Revision 1 on 1 st September 2016 to address these deficiencies. Five...

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In-Flight Flying Control Failure: Indonesian Sikorsky S-76C+ PK-FUP

Posted by on 10:42 pm in Accidents & Incidents, Design & Certification, Helicopters, Human Factors / Performance, Maintenance / Continuing Airworthiness / CAMOs, Oil & Gas / IOGP / Energy, Safety Management

In-Flight Flying Control Failure: Indonesian Sikorsky S-76C+ PK-FUP Sikorsky S-76C+ helicopter PK-FUP (MSN 760582), operated by Hevilift Aviation Indonesia, crashed on 21 March 2015. The final report of Indonesian safety investigators confirms that control was lost after a main rotor servo push rod connection failed after a loss of torque and progressive wear to the point of separation from the rod end. History of the Flight PK-FUP was conducting a daylight pipeline inspection for Total E&P Indonesia from Sepinggan Airport, via the Handil helipad, with eight occupants (two pilots, one engineer, one flight operation officer and four passengers). The Indonesian Komite Nasional Keselamatan Transportasi (KNKT) state in their safety investigation report  that: After reached the cruising altitude of 1,000 feet the PIC [Pilot in Command] handed over the control to the SIC [Second in Command]. The SIC engaged the autopilot and flew maintain cruise altitude and speed of 95 knot. The weather was clear, wind condition was westerly at speed of 5 knots and visibility approximately 8 km. At position approximately 8 nm from CPU [Central Processing Unit facility] the PIC asked the SIC to descend to 600 feet with the rate of 200 feet/minute. While passing 800 feet the helicopter attitude became un-commanded [sic]. The helicopter rolled to the left and pitch up then rolled to the right and pitch down. The SIC lowered the collective and reduced the helicopter speed with intention to recover the helicopter attitude with no success. The PIC took over the control to recover the helicopter until [it]..crash[ed] into swamp. The wreckage came to rest inverted in a tree just over 30 seconds after the first un-commanded movement.  All eight occupants survived, one with serious injuries and the others miraculously with no or only minor injuries. Safety Investigation and Analysis  Analysis of the FDR (a Penny & Giles solid state Multi-Purpose Flight Recorder [MPFR])… ….showed that the helicopter attitude was stable when reaching the altitude of 1,000 feet with heading of 038 degrees. Five minutes later, during descent, the helicopter entered [an] un-commanded attitude. A second after the helicopter started to bank to the left, there was pilot input recorded in the MPFR to counter the aircraft attitude however, the flight control did not respond as expected. The helicopter entered the un-commanded attitude for 31 seconds before ground impact. The MPFR recorded the roll to the left up to 77 degrees, roll to the right up to 52 degrees, pitch up to 45 degrees and pitch down up to 61 degrees. During the un-commanded attitude [sic], unusual sound[s were] recorded [on] video media [a passenger was using a video camera as part of the pipeline survey] and MPFR. The sound spectrum analysis concluded that there was no evidence or progressive damage of propulsion system except there was NR instability observed during the last 35 seconds of the flight. Examination of the wreckage: …revealed that the engines were rotating during impact and no evidence of engine abnormality. The investigation concluded that the engines did not contribute to the un-commanded attitude. Examination of the flying controls however showed that the rod end of forward main rotor servo push rod had separated. The S-76C has three servos, each receiving inputs to a vertical push-pull rod via a bellcrank. The rod end bearing connects “to the push rod via threaded shank and locked by mean...

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Improvised Troubleshooting After Cascading A330 Avionics Problems

Posted by on 8:56 am in Accidents & Incidents, Design & Certification, Fixed Wing, Human Factors / Performance, Maintenance / Continuing Airworthiness / CAMOs, Safety Management

Improvised Troubleshooting After Cascading A330 Avionics Problems On 26 December 2014 XL Airways Airbus A330-243 F-GRSQ suffered a cascading series of failures over the Mediterranean on a flight from Reunion to Marseilles.  The aircraft was at FL380, 280nm south of Athens, when the crew lost all three Inertial Reference Systems (IRS).  This resulted in a decision to divert to Athens, where the aircraft landed safely. History of the Flight The safety investigation body the BEA  say in their report (issued in French only), that shortly after takeoff the flight crew identified that IRS 2 was drifting. They continued to monitor this drift which varied 6 and 15nm, which in itself was not a problem.  About 5 hours into the flight however, IRS3 was switched from ‘navigation’ to ‘attitude’ mode (most likely by the flight crew say the BEA, though the crew do not recall doing that and the FDR does not record the switch position).  The IRS3 data was rejected by the Flight Management Guidance and Envelope Computer (FMGEC), two of which make up the Honeywell Flight Management System (FMS).  However the system does not notify the crew of this.  Consequently, only IRS 1 and the drifting IRS 2 data continued to be used. Two hours later, the autopilot (AP) and autothrottle (ATHR) disconnected.  The BEA believe this was due to the misalignment between IRS 1 and IRS2, Consequentially, as programmed, the FMS removed the position and navigation data from the  Navigation Display (ND). The flight crew were able to retrieve the data by activating the navigation back-up mode.  However, position information on the left hand side displays was lost during “uncoordinated and improvised” troubleshooting.  While the BEA had FDR data, the CVR data had been over written by recording of the later part of the flight.  The BEA believe that the flight crew triggered an in-flight alignment of the three IRSs which, in turn, resulted in a transition of the A330 to direct flight-control law. The BEA say the following factors were considered for the “non-standard crew actions” but “without it being possible to specify their degree of contribution”: Limited flight crew exposure to IRS failure situations. The ergonomics of the Air Data Inertial Reference System (ADIRS) control panel not visually show the irreversible nature of the IRS mode changes The logic of information presentation on the Electronic Centralized Aircraft Monitor (ECAM) which did not articulate the reason for the AP disconnection The presentation of the IRS information on the POSITION MONITOR page of the Multi-Function Control and Display Unit (MCDU) in numerical order (1,2,3) differed from the rotary switch arrangement (1,3,2), which is representative of the architecture system (see the BEA images below). Only one event with similar consequences was found in Airbus’ database (an A320 in 2002). Previous Maintenance The BEA say that that IRS 2 had been reported as drifting on previous flights. IRS 2 was to replaced on 24 December 2014 in Marseilles. However, due to erroneous Functional Identification Number (FIN) tags in the avionics bay, IRS 1 was replaced instead.  The reason for the mislabelling could not be established. The BEA could confirm no maintenance in this area since 2007 (no relevant technical records were available from the time of delivery in 2002 to 2007).  No mislabelling was found in a subsequent fleet check of XL’s two other A330s. Safety Actions The BEA report that Airbus undertook to update their documentation to incorporate the use of the NAV BACK-UP mode in all cases resulting in the loss of ND positions. F-GRSQ was equipped with Honeywell P3 FMS standard (as is 40 to...

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US HEMS EC135P1 Dual Engine Failure: 7 July 2018

Posted by on 11:20 am in Accidents & Incidents, Helicopters, Safety Management, Special Mission Aircraft

US HEMS EC135P1 Dual Engine Failure: 7 July 2018 (UPDATED: 13 April 2020) On the evening of 7 July 2018, at about 21:23 Local Time, Airbus Helicopters  EC135P1  N312SA, powered by two Pratt & Whitney Canada (PWC) PW206B turboshafts, impacted the ground hard after an autorotation following a dual engine failure over Chicago, Illinois. The helicopter operated by Pentastar Aviation Charter as a Part 135 helicopter air ambulance (HAA/HEMS) flight for Superior Ambulance. The US National Transportation Safety Board (NTSB) say in their preliminary report that: The pilot and paramedic sustained minor injuries, the flight nurse sustained serious injuries, and the patient was not injured during the accident. The helicopter sustained substantial damage to the fuselage, tailboom, and main rotor blades. The Accident Flight The NTSB report that: …satellite tracking and air traffic control information revealed the helicopter was traveling northwest from the St. Mary Medical Center on a direct route to Advocate Christ Medical Center about 1,000 ft above ground level. About 5 miles southeast of Advocate Christ Medical Center, the helicopter turned to the right after the pilot requested to return to the Gary, Indiana, airport. About 50 seconds later, the pilot declared a “mayday” and stated the helicopter was going down into a field. The helicopter came to rest upright in a grass area between the Interstate 94 and Interstate 57 interchange. Surveillance video from a Chicago Transit Authority rail platform located adjacent to the accident site depicted the helicopter during the final phase of the autorotation and impact with terrain. The video showed a fire near the number 2 (right) engine during the autorotation. A[n] explosion was observed after the impact with terrain. Local TV News (VIDEO)  Examination of the Wreckage Investigators say that: ….the initial impact was consistent with the fenestron skid cap contacting the terrain first, followed by the landing gear skids and fuselage.  The left landing gear skid was separated and came to rest near the ground scar consistent with the fuselage. The fuselage was crushed upward, and the fenestron assembly was separated at the tailboom attachment location. The pilot seat, paramedic seat, and flight nurse seat were found fully attenuated. Thermal damage was noted on the right engine and main transmission cowling. Significantly: Both engines power turbine wheel blades were missing the outer halves of the blades.  Multiple impact dents, consistent with the fractured turbine blades, were noted inside the exhaust stubs. The No. 1 engine had a 1/2″ by 1/2″ hole in the exhaust stub at the 2 o’clock position forward of the aft firewall, and the No. 2 engine had a 2″ by 1″ hole in the exhaust stub at the 11 o’clock position forward of the aft firewall. Next Steps in the Investigation The helicopter was equipped with Outerlink IRIS.  This provides video, voice and flight data recording as well as satellite communications. The IRIS equipment was sent to the NTSB Vehicle Recorder Lab for analysis. We will update this report as more information emerges. NTSB Investigation Update (9 November 2019) Although the NTSB are yet to issue their probable cause, they have issued several revealing documents and a factual report update. The Accident Flight The NTSB report that: On the evening of the accident, the pilot received a flight request, checked the weather, and performed a preflight inspection for the planned 12 to 13-minute flight. After departure, the...

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Wayward Window: Fatal Loss of a Fire-Fighting Helicopter in NZ

Posted by on 2:02 pm in Accidents & Incidents, Helicopters, Human Factors / Performance, Maintenance / Continuing Airworthiness / CAMOs, Safety Management, Special Mission Aircraft

Wayward Window: Fatal Loss of a Fire-Fighting Helicopter in New Zealand On 13 February 2017 a fire-fighting helicopter was lost in a fatal accident in New Zealand.  In their accident report investigators describe how the sudden loss of a window, as a consequence of flying in an unapproved configuration, may have made the pilot pitch up to slow down, allowing the empty under-slung fire-fighting bucket to strike the tail rotor. History of the Flight On the afternoon of 13 February 2017, wildfires broke out in New Zealand between Lyttelton Harbour and Christchurch in the Port Hills.  A major firefighting effort began the following day.  It involved large ground parties, 12 helicopters and two fixed wing aircraft. Airbus Helicopters  AS350BA  ZK-HKW, operated by Way To Go Heliservices was operating near Sugarloaf Hill.  It was making circuits every 3-4 minutes between a ‘dipping pond’ and the fire. It was equipped with a 1000 litre under-slung ‘Cloudburst 1000’  ‘monsoon bucket’ (an alternative to well known ‘bambi bucket‘).  This was slung approximately 10m below the helicopter. In the early afternoon ZK-HKW crashed while returning to refill its 1000 litre under-slung ‘Cloudburst 1000’  ‘monsoon bucket’ (an alternative to a ‘bambi bucket’). The pilot died in the crash. Safety Investigation The New Zealand Transport Accident Investigation Commission (TAIC) say in their accident report that: The tips of the glass-fibre tail rotor blades were missing. The end of the tail boom, complete with the upper and lower vertical stabilisers, had separated from the helicopter. It was found in vegetation approximately 300m before the main wreckage. All [other] major components of the helicopter were accounted for, except for the window panel from the left rear sliding door. The rubber window seal was retained in the door panel. TAIC comment that: The damage to the tail rotor blades was consistent with their having struck the wire suspension cables of the monsoon bucket where the cables were joined to the lifting strop.  There was corresponding damage on the cable cluster. The bucket and the strop remained attached to the helicopter’s fixed hook. A video recording taken from a camera mounted underneath the helicopter showed the monsoon bucket rising towards the tail rotor. The video recording also showed that an object fell from the helicopter shortly beforehand. A close examination of the images…determined that the object appeared to be light weight, of rectangular form, and highly reflective. It is virtually certain that this was the window that had dislodged from the left rear sliding door. The helicopter was fitted with sliding doors on the left side of the cabin and standard doors on the right side.  Pilots flew the helicopter from the right seat. To further improve the pilot’s view of the underslung bucket while firefighting, all the doors on the right side had been removed and the doors on the left side were closed. The door configuration meant that the window was likely subjected to fluctuating pressure as the helicopter encountered turbulence and wind shear while flying at the estimated 80-90 knots. It is very likely that the window panel was dislodged from the door by a sudden increase in air loading due to turbulence or a change in airspeed. The damage to the tail rotor caused the vertical stabiliser to tear off the tail boom (see below), and the helicopter became uncontrollable and crashed. The pilot had experienced a similar loss of the left rear window...

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