AS350B3 Ditching Japan
Airbus Helicopters AS350B3 Ditching Japan (Excel Air Services JA350D) On 8 June 2018, Airbus Helicopters AS350B3 JA350D of Excel Air Service, ditched c 41 km NW of Naha airport while en route to Aguni airport. The pilot was seriously injured. The Accident Flight The Japan Transport Safety Board (JTSB) explain in their safety investigation report that while in cruise at c 110 kt and 1,000 ft at around 15:25 the pilot heard a warning ‘gong’, the engine governor light (GOV) illuminated and the pilot had to counter a right yaw. Main rotor speed (NR) also reduced. The pilot disengaged the autopilot (AP) and slightly lowered the collective pitch (CP) lever in an attempt to maintain NR. After confirming that NR indicator showed around 370 rpm in warning control range (yellow arc line: between 320 and 375 rpm), the pilot operated emergency control in case of governor failure. The pilot shifted the twist grip to manual operation and turned it to the left; however, the pilot was unable to position NR in normal control range (green arc line: between 375 and 394 rpm), and the altitude of the helicopter kept going down. NR stabilised at around 370 rpm. The pilot felt the flying controls had become heavy,”as in the case that hydraulic system was off”. The pilot [3,474 flight hours total time, 1,887 hours on type] had not experienced [practical] training of emergency control for the case of governor warning light failure, and had [only] verbally confirmed the procedures simulating the failure in regular training. The pilot turned the twist grip only to the left paying attention to avoid an excessive NR, but was unable to increase NR. Because the helicopter did not stop descending and came as close as about 300 ft to the sea surface, the pilot made a decision to ditch at this time. The Flight Manual Supplement for the Emergency Flotation System (EFS) states: Ditching at 10 kt or less is recommended. Ditching must be as horizontal as possible. Ditching with power on requires deceleration to 5 kt or less before lowering the collective lever after ditching. JTSB explain that: At 15:25:30, the pilot sent [a] distress message and manually activated emergency locator transmitter (ELT). The pilot thereafter strongly pulled the cyclic stick to decelerate for ditching and [deployed] the emergency floats at about 50 kt. The helicopter came near to the sea surface in 10 to 20 seconds after sending the distress message, and ditched at the speed of 20 to 30 kt without performing a sufficient deceleration. The helicopter immediately sank to the level of the pilot’s seat. The pilot unfastened shoulder harness and seat belt while dipped in the sea, escaped from the helicopter without putting on a life jacket [which was stored under his seat]. The pilot initially held on to an EFS float bag to await rescue. Fortuitous a SAR helicopter of the Japan Air Self-Defense Force was exercising near-by and it… …received the distress message, arrived near the accident site around 15:39 and found the pilot on the sea. The helicopter had already sank in the sea at this time. The pilot was rescued by the rescue helicopter and was taken to the hospital in the city of Naha via Naha airport around 16:20. When the rescue helicopter arrived at the accident site, it received a weak ELT signal near the site where the helicopter had sank, which...
read moreSAR AW139 Dropped Object: Attachment of New Hook Weight
SAR AW139 Dropped Object: Attachment of New Hook Weight (Sapporo City Fire Department JA17AR) On 16 February 2020 objects were dropped from Leonardo AW139 SAR helicopter JA17AR of the Sapporo City Fire Department Air Corps during rescue hoist training at Ishikari City, Hokkaido, Japan. The Japan Transport Safety Board (JTSB) explain in their safety investigation report (issued 18 February 2021) that the helicopter was undertaking the final of 6 hosting exercises planned for that flight. The right-hand door was opened, a rear crew member attached two connected 5lb ARS Hoist Hook Weights (a total mass of 10 lb, 4.54 kg) to the hook to increase stability and let go of the hoist hook. The weights however “came off from hoist hook hole and dropped from altitude 180 ft (55 m)”. They were subsequently found in the national forest near the airfield. They had not hit anyone but the Dropped Objects Prevention Scheme (DROPS) calculator confirms this as a potentially fatal incident. JTSB Safety Investigation The JTSB report that upon examination no defects were found with either the hoist hook or the attachment hook on the weights, a component also widely used on mountain-climbing gear. The investigators comment that: The weight hook can be opened by squeezing levers on the both side and remains open. When you insert an object to hook, the object pushes the guide and close the hook. The weight hook consists of two hook-shaped parts that are overlapped symmetrically and attached with a shaft, and the spring is pushing the two parts to close from both sides. When the hook is closed, the spring force is applied in a direction to close, and when it is open, the force is applied in a direction to open. When you connect the weight to the hoist hole it is difficult to visually confirm situation of the weight hook whether it is open or closed for the weight hook works inside the hole. The hook weights had only recently been purchased by the Fire Department, differed from the traditional Karabiners and had only been used “a few times”. Upon introducing the weights, rescue members conducted familiarity training to confirm their usability and installation certainty, but did not anticipate the possibility that the weight hook may be disengaged. Fortuitously video footage was available of the incident to aid the investigation. The enlargement of the hoist hook image… …shows that the lever on one side can be seen, but the other side cannot. In addition, the black upper part of the hook seems to be open on its right side. From this, it was confirmed that one side of the hook was open when the weights were released. The image above shows show that the crewmember placing their hands on the lever when attaching the weights to the hoist hook hole. The instruction manual of the hook manufacturer, describes a warning that it should never hold the lever during connection. However, when they purchased the weight[s], no manual was attached. The crew member confirmed they were aware of the need to apply tension to confirm secure attachment but unconsciously omitted that check. During testing, it was found that weights were able to hang as shown below. If the weight was put outside in this state, weights would sway to the left, and therefore, the weight hook would turn clockwise as the arrow indicates. It was confirmed due to the shape of the hook tip, the hoist...
read moreATR 72 Rudder Travel Limitation Unit Incident: Latent Potential for Misassembly Meets Commercial Pressure
ATR 72 Rudder Travel Limitation Unit Incident: Latent Potential for Misassembly Meets Commercial Pressure (Air Contractors, EI-SLG) On 15 March 2011 ATR 72-202 EI-SLG of Air Contractors experienced an uncommanded yaw, resulting in a roll to the left as it accelerated through 185 kt. Directional control was regained and aircraft returned to Edinburgh Airport. Cockpit indications identified a fault with the rudder Travel Limitation Unit (TLU). The aircraft was makings its first flight following a ‘2 Year’ base maintenance check at Edinburgh and was being positioned to Paris. In this article we examine the airworthiness aspects. System Design and Organisational Background The UK Air Accidents Investigation Branch (AAIB) explain in their safety investigation report (issued in July 2012) that: The rudder linkage on the ATR 72 is a mechanical system… The TLU, installed on the rudder rear quadrant shaft, reduces the range of available rudder deflection at airspeeds above 185 kt, in order to limit the structural loads on the rudder. In the full authority (or low speed) position, rudder deflection is not limited; in the reduced authority (or high speed) position, rudder deflection is mechanically limited by the TLU. The TLU mechanism comprises an electrical actuator which drives a pivoting bracket on which two rollers are mounted. In the reduced authority position the actuator retracts, engaging the rollers in two v‑shaped cams mounted on the rudder rear quadrant shaft, to limit the rudder deflection mechanically. In the full authority position the actuator extends, disengaging the rollers from the cams and rudder deflection is no longer limited. Within the ATR family the TLU is unique to the ATR72. The maintenance organisation that performed the check… …had previously been owned by the aircraft operator but both were now sister companies and part of a larger group. Two of the operator’s aircraft had recently experienced significant delays at the Edinburgh facility…. Another of the operator’s aircraft was planned in for maintenance immediately following EI-SLG. The management at the maintenance organisation considered that another delayed aircraft would have been viewed as a major failure on their part and would result in loss of revenue if the following aircraft could not be accommodated. Of note however is that: This operator had a policy of directly purchasing parts from the aircraft manufacturer, and forwarding them to the maintenance organisation. The maintenance organisation considered that this practice would often result in delays, causing a backlog of work towards the end of the maintenance check. During maintenance: A check leader was assigned… This role involved allocation of job cards and manpower, ordering of spares and reporting on the progress of the check. A number of mechanics and LAEs were assigned to each aircraft, and the senior LAE would deputise for the check leader in his absence. The maintenance organisation had a production manager. The production manager was an experienced [Part-66 C Licenced] engineer who had worked for the organisation for two years. In this time he had been promoted to the role of check leader and was subsequently appointed as production manager, responsible for the overall management of the maintenance facility. Noticeably: This post also entailed acting as the Accountable Manager for the company’s Part 145 maintenance organisation approval. In addition to this he also held the post of line maintenance manager. As well as the potential for high workload and distractions from these multiple roles, AAIB note that: This situation represented a conflict of interest between the production manager’s commercial priorities and his obligations as the Accountable Manager. AAIB Safety Investigation After landing… …subsequent visual inspection of the TLU confirmed that one of the cams on...
read moreS-76A++ Rotor Brake Fire
S-76A++ Rotor Brake Fire (N911FK of Trauma Star) On 16 December 2017 Sikorsky S-76A++ N911FK of Trauma Star was damaged by fire near Islamorada in the Florida Keys, shortly after completing a helicopter air ambulance flight to pick up a stabbing victim. The Fire The US National Transportation Safety Board (NTSB) explain in their safety investigation report (issued in February 2021) that… …the flight departed Florida Keys Marathon International Airport (MTH), Marathon, Florida, about 0637 for an air medical trauma patient pickup; the pilot landed at a pre-surveyed landing zone [on a sports field at the Coral Shores High School] at about 0650… The Trauma Star Part 135 General Operations Manual states that for ‘Ground Operations at Off Airport Landing Sites’: Once the aircraft has landed, the pilot will apply the rotor brake and stop the aircraft rotor system. The pilot will then advise the medical crew when it is safe to exit the aircraft. Trained medical crew will supervise the preparation of the patient for loading into the aircraft, including ensuring the patient is adequately secured to the litter, removal of any unsecured sheets or blankets from the litter assembly, etc. Ambulances may bring the patient to the aircraft but will not approach within 30 feet of the aircraft or rotor system. The pilot, who had 5850 hours of total experience, 685 hours on type,… …positioned the engine controls to idle and the main rotor speed (Nr) was less than 60% before he applied the rotor brake to stop the rotors. After the rotors stopped, the paramedic and flight nurse exited the helicopter to attend to the patient. The pilot indicated that after the medical crew departed the helicopter, he noticed that the No. 1 engine temperature was fluctuating with an increase in the inlet turbine temperature, so he shut down the No. 1 engine. The operator reported that, about the same time, the flight nurse noticed dark smoke coming out of the main rotor gearbox cowling area of the helicopter. The flight nurse reported that the smoke was accompanied by sparks, which shortly after turned into flames; she and the paramedic ran toward the helicopter and signalled the pilot about the fire. The pilot reported that he noticed the flight nurse waving her arms and warning of a fire but did not observe any cockpit indications of a fire; however, he shut down the No. 2 engine and observed flames when he partially exited the helicopter. He discharged both engine fire bottles and then exited the helicopter. He stated that the fire continued to burn until fire department personnel extinguished it. NTSB Safety Investigation The thermal damage observed in the main rotor gearbox compartment appeared centered around the rotor brake. The rotor brake control components did not exhibit evidence of anomalies that would have either led to its uncommanded engagement with rotors turning or sustained engagement after disengagement of the rotor brake. Raised material found on the rotor brake disk surface was consistent with fused material from the rotor brake pads. Both forward and aft brake pucks extended when hydraulic pressure was applied to the brake calipers. The forward pucks of the left and right brake calipers did not automatically retract when hydraulic pressure was removed, but they were manually retracted without difficulty. The NTSB note that: The rotorcraft flight manual supplement (RFMS) for the accident helicopter mentioned the possibility of a rotor brake fire if pressure has been applied to the rotor brake system that resulted in a rotor brake puck dragging against a brake disk. However, with...
read moreBEA Point to Inadequate Maintenance Data and Possible Non-Conforming Fasteners in ATR 42 Door Loss
BEA Point to Inadequate Maintenance Data and Possible Non-Conforming Fasteners in ATR 42 Door Loss (Hop! ATR 42-500F-GPYF) On 25 March 2018 ATR 42-500 F-GPYF of HOP! flew from Paris-Orly to Aurillac. At top of descent the 15 kg left Main Landing Gear (MLG) door separated from the aircraft, impacting and damaging the left-hand wing/body fairing. The aircraft was able to make a safe landing. The 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 February 2021) that examination… …of the aeroplane’s left MLG door made it possible to establish that the nut of the door’s rear hinge assembly had unscrewed in service before coming off. The screw then moved backwards which allowed the male hinge to come out of the female hinge resulting in the landing gear door being slightly misaligned with the fuselage. This misalignment increased the aeroplane’s drag. The analysis of the FDR data found that the increased drag and thus the misalignment of the door was present at least from the first level flight at FL110 and that it probably did not exist on the previous flights. This abnormal position of the door also resulted in additional loads on the other landing gear door attachment points, in particular the link which failed under fatigue at the start of the descent. The loss of the link and rear hinge assembly attachment points then introduced substantial loads on the remaining main attachment point, the front hinge assembly, until failure under overload of the male hinge. Once the three main attachment points were no longer effective (link, front hinge assembly and rear hinge assembly), the door swung upwards around hinge No. 1 and struck the fuselage and window. This situation generated the noise heard and jolt felt by people on the plane followed by the failure under overload of this same hinge. The door then separated causing: damage to wing root fairings scratches to a cabin window and the surrounding skin a tear on the lower surface skin of the left flap scratches on lower surface skin of the left wing small dents on vertical stabilizer. The BEA note that: An occurrence in 2013 reported by ATR showed significant similarities… [M]aintenance had been performed on the landing gear doors shortly before the occurrence and that the job card had only been partially applied because of a shift change while the task was being performed. This could have resulted in some of the nuts on the landing gear door hinge assemblies not being tightened. Although the hinge assemblies of the main landing gear doors are not considered as critical parts, these two occurrences show that the simple loss of the nut from the rear hinge assembly can result in the loss of a main landing gear door weighing around 15 kg leading to risks for the aeroplane and also constituting a danger for people and infrastructures on the ground which cannot be ignored. There is sadly often over-enthusiasm for assuming maintenance errors have occurred due to a ‘Failure to Follow Procedures” (FFP), obsessing on classifying how and why personnel ‘violated’ those procedures and applying crude culpability decision aids. This case study shows that approach is very misguided in limiting the potential for holistic systemic improvement. Fortunately, the “sole objective” of BEA safety investigations aims “at improving aviation safety [and] does not presuppose the existence of a misdemeanour...
read moreWire Strike on Unfamiliar Approach Direction to a Familiar Site
Wire Strike on Unfamiliar Approach Direction to a Familiar Site (Air-Glaciers Airbus Helicopters AS350B3 HB-ZCZ) On 11 March 2019 Airbus Helicopters AS350B3 HB-ZCZ of Air-Glaciers struck a with a power line near the Tseuzier dam in Crans-Montana near Sion, Switzerland. The helicopter survived the wire strike with only damage to the leading edge of one main rotor blade. The Serious Incident Flight The Swiss Safety Investigation Board (SUST) explain in their safety investigation report, issued in French on 21 January 2021, that the helicopter was conveying three workers to a dam, to conduct a monthly inspection. The helicopter was equipped with a cable cutter / Wire Strike Protection System (WSPS) as well as a FLARM, a glider/GA traffic warning system that also warns of obstacles programmed in its database. The pilot said he landed at the Tseuzier dam about 50 times in total, once in the past 90 days. [However]…reduced visibility conditions forced the pilot to undertake an approach from the left bank of the dam…the first time he made this approach… Without performing a reconnaissance flight prior to the approach, the pilot intended to fly over the power line he was aware of, then perform the final approach along the dam wall. SUST note that obstacles over 25 m are required to be notified and are available via the obstacle collection system and a Web-GIS Obstacle Map (WeGOM) is updated twice per week. At the time the cable was in the database, but its position was offset by 20-50 metres as show below (since corrected but not a factor in this wire strike). The [operator’s] Operations Manual (OM) A, states that …“A direct approach is permissible provided that the surroundings are reasonably clear and or familiar and that the airspeed is adjusted to a slow enough ground speed.” According to the pilot’s statement, these conditions were met. As the pilot later stated, he was familiar with the line, but he estimated its position a little further north [consitent with the obstacle database] and at a lower altitude in the valley. The FLARM obstacle alert was not integrated into the intercom system and headset audio, so was not heard by the pilot, although it was audible in the cabin. During the approach the wire strike occurred. The pilot did not notice any vibration or engine parameters being exceeded; he continued his approach and landed the helicopter without problem on the planned landing zone. As the weather conditions deteriorated, the pilot does not stop the machine completely but only idled the engine. After a 5-minute flight back to base, damage to the leading edge of a main rotor blade was observed. No other part of the helicopter was hit. SUST Analysis The investigators concluded the pilot was familiar with the area. Although the OM A’s straight-in approach requirements were probably met, the pilot deprived himself of the ability to visually determine the exact position and height of the obstacle using a preliminary reconnaissance flight. Assuming he was familiar with the position and height of the obstacle, the pilot took an increased risk, even in good visibility conditions. The FLARM obstacle alert was on but only audible in the helicopter cabin. Consequently, the pilot did not hear the aural alert when the helicopter approached the power line. This highlights that such an installation as a last safety net is not useful if there is too much noise in the cabin. In this case, it can...
read morePrior Engine Mount Damage Lead to Fatal Aerial Saw Crash
Prior Engine Mount Damage Lead to Fatal Aerial Saw Crash (Rotor Blade LLC, Hughes / MD 369D / 500D N89ZC) On 5 March 2019 Hughes (later MD) 369D / 500D N89ZC, operated by Rotor Blade LLC, crashed near Talking Rock, Georgia, killing the pilot. This occurred during a Part 133 external load flight using a 10-bladed aerial saw to trim trees alongside power lines. The Accident and NTSB Safety Investigation The US National Transportation Safety Board (NTSB) explain in their safety investigation report that three passes were planned (upper, middle, and lower): A witness reported that the pilot performed the upper pass, then returned for the middle pass when the helicopter began to rotate counterclockwise around the main motor mast. It completed one full rotation, and during the second rotation, the helicopter impacted trees and then the ground. Post-accident examination revealed (our emphasis added)… …a fracture of the overrunning clutch outer race and cracks on three of the engine mounts. While two of the three engine mounts cracks were likely a result of impact forces, the cracks on a third [central] engine mount were likely present prior to the accident. The failure of the overrunning clutch subassembly outer race resulted in a loss of power to the main rotor system. Given the helicopter’s low altitude and airspeed at the time of the loss of power, the pilot was likely unable to successfully initiate and perform an autorotative landing. The investigation identified that: Before its installation…the overrunning clutch subassembly had been repaired, which included the installation of a new outer race. The accident helicopter operated with the overrunning clutch subassembly for about 33 flight hours until the accident occurred. Examination of the fracture surfaces revealed signatures consistent with fatigue and subsequent overload. The orientation of the crack in the circumferential plane was consistent with an anomalous bending load, such as an angular misalignment of the drivetrain, that drove fatigue crack initiation. The investigation went on to determine that… …it is likely that the damaged center engine mount was the source of the anomalous bending loads… The 100-hour/annual inspection of the engine mounts could be performed with the engine installed on the airframe, and the operator had done so; however, the presence of the engine could present difficulties for a mechanic in performing a visual inspection, particularly of the forward side of the center engine mount, where the cracks were located. Maintenance records indicated that, in the 9 months preceding the accident, the engine mounts were inspected six times with no anomalies observed. However, when the engine mount cracks may have developed and whether they would have been visible during any of the previous inspections could not be determined based on the available information. NTSB Probable Cause A fatigue failure of the overrunning clutch subassembly due to abnormal bending loads due to cracks on the center engine mount, which resulted in an inflight loss of power. Contributing to the accident was the helicopter’s low altitude and airspeed when the loss of power occurred, which precluded the pilot from successfully performing an autorotation. Previous Accidents Not discussed in this accident report but the 1981 built helicopter had suffered three previous accidents. On 6 November 2009, while operated by Extreme Helicopters, the helicopter lost engine power less than a minute after takeoff in Baxley, Georgia. It rolled over onto its left side during the subsequent autorotation and suffered substantial damage. The pilot told the NTSB this was “main fuel valve was pulled causing fuel starvation to the engine.” On 29 July...
read moreUnanticipated Yaw: Loss of Control During Landing Site Survey
Unanticipated Yaw: Loss of Control During Landing Site Survey (Airbus EC130T2, N130TG) On 3 August 2018 private Airbus Helicopters EC130T2 N130TG lost control while manoeuvring to survey a potential landing site near the Dismal River Golf Club at Mullen, Nebraska. The pilot was uninjured, but the passenger sustained serious injuries and the helicopter was substantially damaged. The US National Transportation Safety Board (NTSB) explain in their safety investigation report that the 61-year-old pilot had just 213 total flying hours, 80 as PIC and 194 on type. The pilot reported the weather was clear and breezy with 15 to 20 knots of wind from the southeast. As the helicopter approached the golf course the helicopter was about 500 ft above the ground, 100 knots, and slowing to 70 knots as he initiated a descent. Evidence from the installed Appareo Vision 1000 image, audio, and data recorder was examined by the NTSB and proved valuable in understanding the accident: The helicopter entered a right turn around a group of buildings. A flagpole visible in the video indicated that the winds were out of the south; the flag was mostly unfurled, and the flag was fully visible. After one right turn, the helicopter started a left turn around the same group of buildings. As the turn begins to tighten in radius the helicopter starts to descend. The ground speed showed a decreasing trend with an indicated airspeed of 30 knots. The heading changed to north, the ground speed decreased, and the airspeed indicator displayed 0 knots. As the helicopter turned to a downwind condition, a left yaw rate rapidly increased and was not arrested, resulting in a loss of yaw control. The pilot stated that he initially added right-pedal during the first ½ of the turn and increased it to full right pedal for the remainder of the rotation. According to the data analysis: At the moment of loss of yaw control, the First Limit Indicator (FLI) read about 6.5 units, the pitch was nose down (about -18 degrees) and quickly became more nose down as the loss of yaw control continued. The pilot made some aft stick inputs around this time. There was a slight right pedal input observed, the right pedal was forward of the left pedal about an inch. As the loss of yaw control continued to develop, the pilot made a slight left pedal input. The helicopter continued yawing to the left and remained nose down (-18 degrees). The left pedal remained slightly forward of the right pedal until the time of ground impact. From the time of the loss of yaw control, the helicopter completed about 1.25 rotations to the left until ground impact. The fuselage and main rotor were damaged on impact. Reflectively, the pilot commented that… …he needed to perform higher, faster, and wider turns. He told the NTSB he “had encountered similar rotations before but was always able to recover”. The pilot was not familiar with the service letter from Airbus [see Safety resource below]. He had completed their course in May at their facility in Grand Prairie, Texas, and he recalled discussion regarding loss of tail rotor control. NTSB Probable Cause The pilot’s inadequate and incorrect anti-torque pedal application during a tight, decelerating turn downwind, which resulted in a loss of yaw control. Safety Resources: Unanticipated Yaw NTSB note that: In February 2005, Eurocopter released Service Letter No. 1673-67-04 “Reminder concerning the...
read moreFlybe Fume Event (Part 1): Compressor Wash Maintenance Human Factors Case Study
Flybe Fume Event (Part 1): Compressor Wash Maintenance Human Factors Case Study (ERJ195 G-FBEJ) On 28 February 2019 Flybe Embraer ERJ-195 (ERJ-190-200 LR / E195) G-FBEJ was commencing takeoff in Exeter, bound for Alicante, when the flight crew detected a sweet-smelling odour and observed smoke entering the cockpit. The takeoff was abandoned and after smoke and fumes were reported in the cabin an evacuation commenced. This article, the first of two, will examine the cause of the fumes. The second will examine the evacuation. The Safety Investigation The UK Air Accidents Investigation Branch (AAIB) explain in their safety investigation report that: During overnight maintenance on the night before the accident, an engine compressor wash was carried out on G-FBEJ’s No 1 [GE CF34-10] engine. A high-power engine ground run was not performed following the compressor wash, resulting in residual cleaning solution remaining in the compressor bleed air ducts. This can lead to fumes or unusual odours entering the cockpit and cabin. There is sadly often over-enthusiasm for labelling occurrences as ‘Failure to Follow Procedures” (FFP) events and obsessing on classifying how and why personnel ‘violated’ procedures, applying crude culpability decision aids. This case study shows that approach is very misguided in limiting the potential for holistic systemic improvement. Fortunately, the “sole objective” of AAIB safety investigations “is the prevention of accidents and incidents, without the apportionment of blame or liability”. This investigation therefore did not fall for the biases that can occur in relation to procedures. The Safety Investigation: Compressor Wash Procedures General Electric recommends engine cleaning to reduce contaminant build-up and maintain engine performance. Compressor washes are performed by maintenance personnel, using a wash rig, which uses either water or a water and detergent mix. The engine wash rig used on G-FBEJ was fitted with two pressurised fluid tanks, one which contained water and the other a water/detergent mix. During operation, the fluid can be directed into a water-wash manifold installed on the engine, to dispense water/detergent into the compressor. The maintenance personnel used Engine Service Manual (ESM) task 72-00-00-100-801 ‘Engine performance recovery,’ revision date 31 March 2016. The task requires a minimum of two people, one to operate the engine and system controls in the cockpit and one to operate the compressor wash rig. The ESM advises that: For some environments, washing with a cleaning solution … may be more effective than washing with water only….If a cleaning solution is used, it is important to follow instructions for rinsing and drying-out the bleed systems. A caution states: FAILURE TO ADEQUATELY DRY THE INTERNAL ENGINE AIRFLOW COMPONENTS AFTER AN ENGINE WASH CAN RESULT IN ODOR-IN‑CABIN EVENTS WHICH HAVE CONTRIBUTED TO SITUATIONS SUCH AS AIR TURNBACKS AND ABORTED TAKEOFFS. PROPER ENGINE DRY-OUT IS IMPORTANT TO PREVENT THOSE SITUATIONS. The ESM lists several detergents, including Turco 5884 used by the operator, which the ESM states should be mixed one part detergent to four parts water (i.e. 20% detergent). Rinsing should be with water only. The AAIB go on (our emphasis added): One subtask describes the procedure to wash the internal engine airflow components with water only and an alternative subtask describes the procedure to do the wash with a cleaning solution. It recommends that to get the best cleaning results, two washes should be done as well as a soak period between application of the cleaner, followed by two rinses to make sure that the cleaning solution is removed. A further subtask...
read moreHuman Factors of a Mali Mid Air Collision
Human Factors of a Mali Mid-Air Collision (MAC): ALAT Tiger and Cougar, Operation Barkhane, near Ménaka On 25 November 2019 two French Army helicopters, Airbus EC665 Tiger (Tigre) HAD 6017/F-MBJQ and Airbus AS532UL Cougar 2272/F-MCGE, collided in mid-air during a combat operation as part of Operation Barkhane, near Ménaka in Mali. The two crew of the Tiger and the 11 occupants of the Cougar died in the accident. The Events Leading to the MAC Investigators of the BEA-Etat (BEA-E) explain in their safety investigation report (issued on 29 January 2021 in French only) that at around 17:00 Local Time helicopter crews at bases in Gao and Ménaka were put on alert after a ground unit had contact with the enemy. The intention was to launch two Gazelles from Ménaka and two Tigers from Gao. With four aircraft deployed it was decided to also deploy a Cougar from Ménaka with an Air Mission Commander (AMC). The Cougar also had six troops onboard to provide an IMEX, immediate extraction, capability. The Gazelles departed at 17:31 followed by the Cougar at 17:40. The Tiger’s departed at 17:37. This was to be a night operation, sunset was at 17:16, with the crews utilising Night Vision Googles (NVGs) and operating only with formation lights (visible from above and behind only). The Gazelles arrived on-scene at 17:50, followed by the Cougar 10 minutes later, with the Tigers expected at c 18:25. French troops were to the south side of a wadi (a small river valley). The engagement had had triggered a large ground fire to the north of the wadi and the helicopters from Ménaka initially search for enemy combatants fleeing behind the fire. The Gazelles identified a point of interest, called a zone of action (ZA), several miles north of the fire. At 18:19 the AMC… …asked the Tigers and Gazelles to stay north of the area, the Tigers to stay west of the wadi and the Gazelles to the east. All of the following AMC communications relate to mission management and rules of engagement, in relation to ground troops who insistently request fire, and the Ménaka command post. The Cougar then goes north then east to fly over the wadi east of the ZA. At 18:23 the leader of the Tiger flight announces that he will climb to a height of 2,000 ft (i.e. around 3,000 ft AMSL) and loiter 2 nm west of the area (by implication ZA). The Cougar and Tigers coordinate TACAN channels and a pressure setting of 1,013 hPa. At this point the Cougar is at 3,000 ft AMSL and the Tigers at 2,800 ft. The AMC then proposes a withdrawal of the Gazelle and the Cougar as no longer necessary. At 18:26 the Tigers and the Cougar had all climbed slightly, with the Tigers 2 nm west of ZA and the Cougar 8 nm to the north-east. Shortly after the Cougar crosses the wadi and heads south-west without announcing this movement. At 18:29 the Tigers split so that one aircraft can overfly French troops at their request. The AMC is however busy on another channel at this point. The lead Tiger goes into an orbit around ZA at 3,000 ft before climbing to 3,300 ft. The Cougar, still at 3,200 ft, now commenced its unannounced orbit of ZA. At 18:33 the Cougar and lead Tiger passed in opposite directions separated 300 m horizontally and 100 ft vertically at 66 and 100 knots respectively. Two minutes later, on...
read more
Recent Comments