Swinging Snorkel Sikorsky Smash: Structural Stress Slip-up
Swinging Snorkel Sikorsky Smash: Structural Stress Slip-up (Brainerd Helicopters Sikorsky UH-60A Black Hawk N9FH Firefighting STC MCF) On 25 May 2021 Sikorsky UH-60A Black Hawk N9FH of Brainerd Helicopters Inc (parent company to Firehawk Helicopters) crashed near Leesburg International Airport (LEE), Florida. This was during the post-maintenance check flight after installation of a snorkel equipped aerial firefighting system. The restricted category helicopter was destroyed and all 4 occupants died. The US National Transportation Safety Board (NTSB) issued their safety investigation report on 19 April 2023. The Modification Eight days earlier the snorkel/tank system had been installed on this ex-military restricted category helicopter in accordance with a Blackhawk Mission Equipment LLC (BME), Federal Aviation Administration (FAA) Supplemental Type Certificate (STC), number SR00933DE, approved by the by the FAA Denver ACO. BME is a subsidiary of Brainerd Helicopters. Several days of ground testing and calibration were performed before the accident flight, which was the first flight after the 925 gallon carbon composite cabin tank and the external snorkel were installed. The snorkel has non-retractable 15 foot long, 6 inch diameter, flexible hose which hangs from the left side of the tank to allow water uplift in a low hover. The snorkel is outboard of a water chute, that extends out of the left cabin door, as the means to empty the tank. The snorkel is attached to the tank at metal nozzle port which is secured to the tank via a by 8 AN4 bolts fastened to a backing nut plate at carbon fibre flange. The snorkel connects is attached to the nozzle port by a two lever cam-lock (the ‘coupler’). A 7.5 hp pump is mounted at the lower end of the hose. A power cable for the pump and a lightning protection cable run down the length of the snorkel and are secured using nylon zip ties. The snorkel hose and pump assembly [mounted at the bottom] weighs 137.5 pounds. The Fatal Accident Flight The purpose of the local flight was to check the operation of the newly installed fire-fighting system. The helicopter made six uneventful passes in front of the operator’s hangar at LEE and dropped water that was picked up from a lake adjacent to the airport. On the seventh pass, an employee of the operator noticed that the snorkel was swinging. He called the LEE air traffic control [ATC] tower and told the controller to ask the pilot to slow down and land immediately. Before the controller could contact the pilot, the helicopter transitioned to forward flight, gaining altitude and airspeed. During the helicopter’s last pass another witness saw the snorkel swinging in a large circle that came “very close” to the main rotor blades. The employee who contacted ATC said the snorkel was “violently” swinging, then heard a loud bang and… …saw pieces of the helicopter, including the tail section, separate from the helicopter. Afterward, the helicopter started to spin and descended below the tree line. The employee then heard an explosion and saw smoke rise above the tree line. The wreckage was contained in a 31-foot diameter vertical impact crater…in a localized swamp approximately 1,000 feet southeast from the approach end of Runway 3…and had been consumed by fire. The vertical tail, tail rotor, stabilator, and aft portion of the empennage was located about...
read morePoor Contracting Practices and a Canadian Helicopter HESLO Accident
Poor Contracting Practices and a Canadian Helicopter HESLO Accident (Heli-Express Airbus AS350B2 C-GHEX at Hydro-Quebec Powerline Worksite) On 11 May 2021, Héli-Express Airbus AS350B2 C-GHEX was conducting Helicopter External Sling Load operations (HESLO) flights from a staging area to a 315 kV powerline maintenance site, northeast of Les Escoumins, Quebec. During one HESLO flight the loadmaster notified the pilot by radio from the ground that the load was oscillating. The pilot expected the load would stabilise as the helicopter accelerated. At an airspeed of c65 knots, the load struck the tail boom however. The pilot pitched up to slow the helicopter and jettisoned the load which then struck the tail rotor. The pilot subsequently lost control of the helicopter and made a forced landing in sparsely wooded rugged terrain. The pilot suffered serious injuries. The helicopter was contracted to GLR a specialised powerline construction and maintenance company, who were contracted by power utility Hydro-Québec. The Transportation Safety Board of Canada (TSB) discuss important contracting issues and commercial pressures in their safety investigation report (issued 10 January 2023). The Safety Investigation We start by considering the last portion of the flight, after the load impacted the helicopter. But to understand why the load behaved as it did we then step right back to understand the organisational factors that were influencing the operation. Safety Investigation: The Flight After the Load Instability Examination of the load confirmed that it was struck in its understated by a tail rotor blade as the blade rotated backwards. The TSB explain that after the load was jettisoned: The pilot immediately realized that the anti-torque pedals were no longer allowing him to control the yaw, and he quickly experienced difficulty maintaining control of the aircraft. As part of their recurrent training the pilot had practised a technique described in the Rotorcraft Flight Manual that assumed a loss of tail rotor control (but not a loss of tail rotor thrust). In such a case, it is still possible to land with the engine running. The absence of tail rotor thrust cannot be reproduced in flight for training purposes (Héli-Express do not appear to use simulators). With a loss of tail rotor thrust… To land, the pilot must conduct an autorotation while shutting down the engine. As the pilot did not think he had lost the tail rotor… After regaining speed, the pilot headed to a landing strip near the staging area to land with the engine running, like he had learned to do in training. However, after losing and regaining control of the aircraft’s yawing motion twice while heading to the landing strip, his speed and altitude were too low to take back full control of the aircraft when he lost control of the yawing motion a 3rd time. When power was cut, the helicopter was likely at a height that could not sufficiently dampen the autorotational descent… TSB note (our emphasis added) Héli-Express’ training program also includes ground and flight training on the transport of Class B external loads [i.e. suspended loads that can be jettisoned] and operations near high-voltage transmission lines, including flying under the lines. However, the exercises for practising flying near or under high-voltage transmission lines do not include practising transporting a sling load in this particular environment. The pilot had been employed by...
read moreDouble Trouble: Offshore Surveillance P68 Forced to Glide
Double Trouble: Offshore Surveillance P68 Forced to Glide After Power Loss 11 nm Offshore (Réunion Fly Services Vulcanair P68C F-ORET, Mayotte) On 12 December 2021 Vulcanair P68C F-ORET of Réunion Fly Services suffered a double engine power loss event off the French Indian Ocean island of Mayotte. As the aircraft was conducting a border patrol mission for the Prefecture of Mayotte the investigation was conducted by Le bureau s’appelle désormais Bureau Enquêtes Accidents pour la sécurité de l’aéronautique d’État, the French state aircraft accident investigators, the BEA-É. The Serious Incident Flight In their safety investigation report (issued in French only) they explain that the aircraft took off from Dzaoudzi Pamandzi airport, Mayotte at 07:26 Local Time operating under EASA Part-SPO regulations. Mayotte is midway between Madagascar and the Comoros islands. On board were a pilot and an observer and the aim was to conduct a maritime surveillance mission at 500-1,200 feet. Shortly after, c12 nm to the southeast, at an altitude of 800 ft, the pilot heard an abnormal noise from the left (no 1) engine and observed an “oscillatory movement of the propeller spinner”. Concerned at the possible release of debris the pilot initiated an in flight shutdown of that engine and a return to base. Shortly after, 11 nm from the airport at 450 ft, the right (no 2) engine suffered a loss of power and cut out. Four attempts to restart that engine failed to achieve more than a brief period of running and an attempt to re-start the left engine also failed. The pilot ultimately successfully glided to Dzaoudzi Pamandzi airport and made a safe landing. Safety Investigation The BEA-É comment that the pilot was experienced on twin-engine aircraft, also an instructor and was used to demonstrating and carrying out engine failure exercises. The investigators note that this experience may have paradoxically encouraged early shut down of the no 1 engine before gaining more height. In contrast, the failure to restart the left engine was, in the opinion of the investigators, most likely due to an surprisingly hurried attempt but crucially without use of the checklist that may have resulted in omission of one of the series of steps necessary. The report gives no detail on what sea survival measures were in place for this operation. No 1 Engine Failure Upon disassembly damage was found to the propeller spinner support. Investigators concluded that the origin of the damage was misalignment of the low pitch thrust bearing tightening nut, in turn causing longitudinal misalignment of the spinner resulting in the damage found. This failure is not further elaborated upon. No 2 Engine Failure The aircraft had been parked outside for the 12 days since it arrived on the island. On the first 11 evenings it had been refuelled from 195-litre AVGAS 100 LL drum stock. Only on the evening prior to the accident was the fuel not topped up. That evening the aircraft was parked overnight facing east on an apron with a slight slope to the south, with c300 litres of fuel evenly distributed in the two wing tanks (the maximum capacity is 538 litres). Each engine is usually connected to the corresponding wing tank. It is possible to modify this configuration flight by connecting an engine to the opposite tank by means of the fuel selector...
read moreTwisted Firestarters
Twisted Firestarters in this article we look at wo occasions a helicopter has triggered a bush fire. In the first the helicopter succumbed to the flames. In the other case the helicopter fled the scene and the environment suffered. Robinson R44 Northern Territory, 22 June 2022 This R44 was conducting a geophysical survey north of Alice Springs. The survey involved landing every 1 km to collect data. On board were the pilot and a survey field technician. According to the Australian Transport Safety Bureau (ATSB) occurrence brief: At about 1000 local time, the pilot landed in an area of spinifex grass and the field technician disembarked the helicopter to carry out their survey tasks. The technician reported that, after setting up the equipment, they looked up and noticed flames under the helicopter. It was reported that the helicopter’s engine bay was positioned close to an area of dry spinifex and the heat from the engine’s exhaust ignited the grass. The ensuing fire spread very quickly, engulfing the helicopter. The pilot vacated the aircraft and sustained minor burns to their leg while attempting to retrieve a satellite phone on board. The helicopter was destroyed. The ATSB noted they were aware 5 occurrences in the preceding 10 years where a Robinson helicopter has been destroyed by grass fire. The R22 and R44 Pilot Operating Handbooks contain a warning: Do not land in tall dry grass. The exhaust is low to the ground and very hot; a grass fire may be ignited. Australian Army NH Industries NH90 (MRH-90 Taipan), Namadgi National Park, Australian Capital Territory, 27 January 2020 The military NH90 was supporting local civil authorities when it landed in the Orroral Valley within teh national park so crew members could ‘disembark for a short break‘. However a landing light caused a grass fire. The aircraft suffered significant damage but took off and flew back to Canberra. It landed safely and in “little over an hour…Defence public affairs was directed to start developing a holding statement and talking points.” The grass fire had however developed into what was capital city Canberra’s “most serious” bushfire threat since 2003 that consumed more than 7,900 hectares. Critical to the fire’s rapid development was the failure of the helicopter crew to raise the alarm for c45 minutes (i.e. until they landed). A lack of precise information sowed confusion as fire crews were dispatched to different parts of the national park in attempt to locate and extinguish the blaze. The title of the article is a reminder of your nan’s favourite 1990s bad boy, The Prodigy‘s Keith Flint. We will remain alert to any opportunity to reference Skin or PJ Harvey in future titles. Safety Resources The European Safety Promotion Network Rotorcraft (ESPN-R) has a helicopter safety discussion group on LinkedIn. You may also find these Aerossurance articles of interest: South Korean Fire-Fighting Helicopter Tail Rotor Strike on Fuel Bowser S-76A++ Rotor Brake Fire USAF RC-135V Rivet Joint Oxygen Fire C-130 Fireball Due to Modification Error Competitive Behaviour’ and a Fire-Fighting Aircraft Stall Short Sling Stings Speedy Squirrel: Tail Rotor Strike Fire-Fighting in Réunion Wayward Window: Fatal Loss of a Fire-Fighting Helicopter in NZ Helicopter Tail Rotor Strike from Firefighting Bucket Maintenance Issues in Fire-Fighting S-61A Accident Korean Kamov Ka-32T Fire-Fighting Water Impact and Underwater Egress Fatal Accident Firefighting AW139 Loss...
read moreManaging Interruptions: HEMS Call-Out During Engine Rinse
Managing Interruptions: HEMS Call-Out During Engine Rinse – Panel Lost (ANWB Airbus EC135T2+ PH-MAA) On 7 February 2022 air ambulance Airbus Helicopters EC135T2+ PH-MAA of ANWB Medical Air Assistance suffered the in flight loss of an engine inspection panel shortly after departure from Groningen Airport. According to the Dutch Safety Board (DSB) safety investigation (issued in March 2023), the operator conducts an engine rinse “every 5 flying hours / 3 days, or after flights over sea and/or a polluted environment”. This involves the aircraft commander in the cockpit and a second person operating the necessary ground support equipment. The investigators explain that: The procedure required the engine cowlings of the EC135T2+ to be opened in order to access the compressor rinse connection and to be closed after the rinsing procedure was completed. The…procedure also stipulated a plan in case of a Helicopter Emergency Medical Service (HEMS) scramble during the rinsing procedure. In this case a call-out did indeed interrupted the task. Shortly after take off… …the pilot heard a noise and suspected the helicopter had struck a bird. Another ANWB EC135T2+ had indeed suffered a bird strike on 14 January 2021. Investigators note that: There were no indications or warnings in the cockpit of a helicopter system malfunction and the commander decided to continue the flight. However shortly after the call out was cancelled anyway and the helicopter proceeded to return to base. Only after landing was an engine inspection panel found to be missing. The investigators conclude It is likely that the right engine cowling was not properly closed after the engine compressor rinsing procedure was interrupted by a HEMS scramble. Consequently, as a result of aerodynamic overload, it departed the helicopter during the flight. Our Observations It is good that the operator’s engine rinse procedure reportedly considered the task could be interrupted by a call-out. A lazy analysis would be to simply conclude there was a ‘failure to follow procedures’. That is lazy because: the DSB don’t actually describe what was expected in the event of an interruption it fails to recognise that by their very nature interruptions and distractions break and disrupt procedural flow. For this specific task one advantage is that it needs two people, so there are two people who can be used to cross-check key steps to return the aircraft for flight (e.g. disconnecting GSE, securing panels etc). Safety Resources The European Safety Promotion Network Rotorcraft (ESPN-R) has a helicopter safety discussion group on LinkedIn. You may also find these Aerossurance articles of interest: After Landing this HEMS Helicopter Suddenly Started to Slide Towards it’s Hangar… Human Factors of Dash 8 Panel Loss EC120 Forgotten Walkaround Distracted Dynamic Rollover US HEMS EC135P1 Dual Engine Failure: 7 July 2018 Dusk Duck: Birdstrike During Air Ambulance Flight Limitations of See and Avoid: Four Die in HEMS Helicopter / PA-28 Mid Air Collision EC135P2 Spatial Disorientation Accident HESLO EC135 LOC-I & Water Impact: Hook Confusion after Personnel Change Air Ambulance Helicopter Fell From Kathmandu Hospital Helipad (Video) Air Ambulance B407 Hospital Helipad Deck Edge Tail Strike During Shallow Approach US Air Ambulance Helicopter Hospital Heliport Tail Strike Air Methods AS350B3 Air Ambulance Tucson Tail Strike NTSB on LA A109S Rooftop Hospital Helipad Landing Accident Helicopter Destroyed in Hover Taxi Accident Air Ambulance Helicopter Downed by Fencing FOD Ambulance / Air...
read moreHESLO AS350 Fatal Accident Positioning with an Unloaded Long Line
HESLO H125 / AS350B3e N755AE Fatal Accident Positioning with an Unloaded Long Line On 29 July 2020, Airbus Helicopters H125 / AS350B3e N755AE of St Louis Helicopter was destroyed, and the two occupants killed, in an accident near Pioche, Nevada. According to the US National Transportation Safety Board (NTSB) safety investigation report (issued 16 March 2023) the helicopter had landed on a mountain ridge (at an elevation of c 6,741 ft AMSL) during a survey prior to Helicopter External Sling Load Operations (HESLO) schedule for that day to move equipment to a mobile phone cell tower site. The accident flight was to be a c3 minute flight down from the ridge to a fuel truck to refuel (the fuel truck had been unable to drive any closer to the work site). On board were the pilot (owner of the company and who had 12,500 hours of total flight time) and a passenger. A witness reported that…a cable that was laid out on the ground in front of the helicopter. The pilot stated to him that the cable was 70 feet long. The witness left the pilot and passenger at the helicopter and drove away; shortly thereafter, he received a phone call about smoke in the vicinity and learned that the helicopter had crashed. The helicopter came to rest on its right side in heavily wooded terrain c 630 m from the fuel truck.. The aircraft was equipped with a Crash Resistant Fuel System (CRFS). This suffered some impact damage, but there was no evidence of any fuel loss. Examination…revealed that the long line was entangled with the tail rotor, which had separated from the helicopter. One tail rotor blade remained attached to the tail rotor; the other blade was not located. The tail boom was broken off and partially attached at the lower aft bulkhead by control cables. The tail cone/vertical fin assembly was found about 365 ft from the main wreckage and exhibited evidence of cable abrasion. The engine data recorder…indicated that the engine was placed in flight, then reduced to idle near the end of the recording. During this sequence, the main rotor speed decayed below that necessary to maintain lift. Examination of the flight controls and engine, as well as review of recorded engine data, revealed no evidence of mechanical anomalies that would have precluded normal operation. The helicopter was equipped with an Appareo Vision 1000 cockpit video recording device. The removable memory SD card was found to be blank. When the internal memory card was downloaded it contained data from 25 January 2020, 6 months earlier. Appareo identified several electrical system reasons this may not have occurred (including the circuit breaker being open). However: A return trip to the accident helicopter at the wreckage facility was attempted, however due to COVID-19 travel restrictions, and other factors, it was not conducted… So we are sadly none the wiser on this failure. NTSB conclude that… …it is likely that the pilot failed to achieve adequate clearance between the long line and terrain before descending downhill toward the fuel truck, which resulted in the helicopter’s long line, becoming entangled with the tail rotor, and a subsequent loss of helicopter control. Remarkably there is no comment on whether the longline was weighted or not. While an unweighted long line could...
read moreCustoms Training Loss of Control While Climbing Away from a Quick Stop
Customs Training LOC-I While Climbing Away from a Quick Stop (CBP Airbus AS350B2 N841BP) On 13 May 2021 Airbus AS350B2 N841BP of US Customs and Border Protection (CBP) Air and Marine Operations (AMO) was destroyed in a training Loss of Control – Inflight (LOC-I) accident at Yukon, Oklahoma. Both pilots escaped injury but the aircraft was consumed by a post crash fire. The Accident Flight According to the US National Transportation Safety Board (NTSB), who issued their safety investigation report 19 January 2023 the pilot under instruction had been enrolled on CBP’s Initial Pilot Certification course for the AS350B2 at the CBP National Air Training Center (NATC) in Oklahoma City. The student was aged 45, held a CPL and had 1,200 hours total, 620 hours on type. The instructor was 40 and had 6,000 hours total, 1,000 on type. The instructor reported for duty at c11:30 Local Time and started preparing with the student at 12:30 for 2 flights. The aircraft departed at 14:45. The pilot under instruction was in the right hand seat, The flight departed the Will Rogers International Airport (KOKC) and proceeded to the Clarence Page Municipal Airport (KRCE) to conduct training maneuvers. After arrival at KRCE, the flight crew conducted several approaches to the airport including confined area and pinnacle approaches. They then conducted several simulated emergencies, each of which required the helicopter’s hydraulic system to be turned off and then turned back on at the conclusion of the procedure. Readers should note that: The hydraulic system was turned off and on using the hydraulic cut-off switch, an unguarded push-button switch mounted on the end of the pilot’s collective stick. Next… …the flight crew proceeded to conduct a series of “quick stops.” After the third quick stop, the pilot heard a radio call indicating an airplane was on final approach to land on the runway they were using, and the flight instructor indicated that they would clear the runway. The pilot [under instruction] added that he completed a final quick stop and immediately entered a climbing left turn. At this point the pilot under instruction noticed the helicopter was yawing to the left. He was unable to correct that with a pedal input. When the pilot [under instruction] adjusted his grip on the collective, he felt the hydraulic cut-off button with his thumb as he prepared to reduce collective. As he tightened his grip on the collective, “the hydraulics came offline aggravating the left yaw into a hard left spin.” The controls were stiff, and the flight instructor told him to turn the hydraulics back on. The pilot “intentionally pressed the [hydraulic cut-off] button but felt no effect.” He pressed the button a second time, but the hydraulic light on the caution warning panel remained illuminated, so he pressed the button a third time. However the flight instructor stated that during the last quick stop “the helicopter slowed normally but then started a left yaw about 25 ft above ground level”. As the helicopter yawed to c 30° left the instructor “pushed forward on the cyclic to gain airspeed”. Its not clear from the NTSB report if he verbalised that intervention. He stated that “as the aircraft was recovering, the control loads instantly became excessive” and “noticed the hydraulic light on the caution warning panel...
read moreDusk Duck: Birdstrike During Air Ambulance Flight
Dusk Duck: Birdstrike During Air Ambulance Flight (Reach H130 N415RX) On 12 December 2022 air ambulance Airbus H130 / EC130T2 N415RX of Reach Air Medical Services was damaged in a birdstrike north west of Yuba City, California. According to the US National Transportation Safety Board (NTSB), who issued their safety investigation report uncharacteristically quickly on 9 February 2023: The pilot in the helicopter reported that, during cruise flight [at 1,500 ft AGL] at dusk with night vision goggles on, he encountered a flock of birds at 1,500 ft above ground level. As the pilot initiated a climbing left turn to avoid the birds, he heard a loud bang accompanied by a pain in his left leg. The helicopter then began to vibrate, and the pilot initiated a precautionary landing in a nearby field without further incident. Bird remains were located throughout the pilot side of the cockpit. The helicopter sustained substantial damage to the windshield. Fortuitously the bird struck low on the windscreen rather than at head height and only one bird of the flock struck the helicopter. Neither the pilot nor the two other occupants were injured. Even though part of the bird was recovered, disappointingly the bird species and therefore its likely size, was not recorded by NTSB (other than a photo caption saying ‘duck’). Safety Resources EASA have issued Safety Information Bulletin SIB 2021-07 on Bird Strike Risk Mitigation in Rotorcraft Operations and accompanying safety promotion material. In a presentation on behalf of the Rotorcraft Bird Strike Working Group (RBSWG) to the 11th EASA Rotorcraft Symposium in December 2017 it was revealed that in the US 94% of the current helicopter fleet is made up of types that never needed to meet a bird strike requirement. A helicopter accident (discussed below) and the Hudson A320 ditching, both in January 2009, were likely causes of a big increase in all wildlife strikes reporting across the US helicopter fleet.While fixed wing aircraft predominantly strike birds during take-off and landing, two thirds of rotorcraft strikes occurred during the en route phase (where kinetic energy is highest). Only 8-9% occurred during approach and 9-10% during climb. The presentation went on: The largest single component struck by birds is the windshield with 47% on Part 27 and 40% on Part 29. 84-85% of all bird strikes occurred on components forward of the main rotor mast. This includes the main rotor which experienced 30%-33% of the strikes reported. Not one single record exists for windshield penetration on Part 29 rotorcraft certified to the FAA bird strike airworthiness standard established over 21 years ago. This is statistically significant. For newly manufactured and existing rotorcraft, the RBSWG proposed to use a Risk-Based Safety-Tiered approach that scales the bird strike regulation based on the maximum number of occupants onboard. As the number of occupants increases, so does the risk exposure. They also recommend: Reduce airspeed when practical Increase altitude as quickly as possible and practical Use taxi and landing lights They also say: The location of bird concentrations during seasonal migrations and the local bird nesting and roosting habitats, should be made available to the rotorcraft operator/pilot for preflight planning to minimize the potential for bird strikes. Air carriers and general aviation operators working with the Flight Safety Programs and Flight Service Briefing should identify and publish the known locations and probability of bird concentrations. This information on...
read moreUrgent Exit Required: A Helideck Incident
Urgent Exit Required: A Helideck Incident (Omni Sikorsky S-76C+ PR-SEC) Vessels and mobile installations in the UKCS are currently completing a long anticipated helideck upgrade to introduce the latest Rev 9b of the Helideck Certification Agency (HCA) standard of Helideck Monitoring System (HMS) with deck repeater lights. This serious incident in Brazil is a reminder of why this HMS upgrade is essential. On 28 June 2015, Omni Taxi Aero Sikorsky S-76C+ PR-SEC, under contract to Petrobras, had to make a sudden departure from the deck of pipelaying vessel Kommandor 3000, almost colliding with the vessel’s superstructure, after the vessel had changed heading. The aircraft was undamaged and the occupants unharmed. The helicopter damaged the helideck net. The Incident Brazilian accident investigation agency, the Centro de Investigação e Prevenção de Acidentes Aeronáuticos (CENIPA), explain in their safety investigation report (avaible in Portuguese only) that the offshore helicopter had departed from Macaé Airfield (SBME), RJ at 10:30UTC with two pilots and four passengers onboard. Before landing, the [Kommandor 3000’s] radio operator informed [the helicopter crew of] the wind conditions (080°/17kt), the ship’s heading (351°) and the values of pitch, roll and heave. On that occasion, the first consultation was made on the possibility of changing the bow of the vessel after landing. The aircraft landed at 11:40UTC. The Aircraft Commander was Pilot Flying (PF) and remained at the controls while rotors running on the helideck. The four outbound passengers disembarked and four inbound passengers boarded. During this time, the ship’s radio operator again questioned the crew about the 096° turn to heading, and the [aircraft] captain agreed with the manoeuvre. With the passengers on board, the maneuver was carried out as requested. Thus, the wind, which before landing was incident laterally on the vessel, became a bow relative to the ship, and abeam relative to the aircraft. During the vessel’s turn CENIPA say the wind was 29 knots and the vessel was “struck by a wave”, which caused an “aggressive…pitch-up, propelling the aircraft upward and to the right”. The aircraft skidded across and damaged the deck net. The Aircraft Commander perceived the motion as the start of a dynamic rollover towards the superstructure and so wisely initiated an immediate take off. After losing contact with the helideck surface, the aircraft banked and moved dangerously to the right, passing very close to the main structure of the ship, indicating a risk of collision. Safety Investigation The investigation was hampered because the Honeywell Cockpit Voice and Flight Data Recorder (CVFDR) was not functioning during the incident flight, for reasons that were not determined. The investigators did however discover that 10 minutes prior to the landing, the earlier generation HMS was already displaying a red warning on the vessel’s bridge that at least one motion parameter was outside of limits. Other Occurrences We have previously discussed an accident from February 2014 in Brazil where another Petrobras chartered S-76C+ was damaged landing on a vessel without being warned that the HMS was showing exceedance: Helideck Heave Ho! (BHS Sikorsky S-76C++ PR-CHI). That prior investigation was only released 16 November 2021 (in Portuguese only), far too late to have helped prevent the 2015 near miss. CHC AS332L G-BKZE suffered a rollover on the helideck of drillship West Navion in the North Sea on 10 November 2001. In that...
read moreS-92A Offshore Landing Obstacle Strike: CENIPA Report
S-92A Offshore Landing Obstacle Strike: CENIPA Report (BHS S-92A PR-CHR on Sevan Brasil) On 15 April 2017, Sikorsky S-92A PR-CHR of CHC‘s Brazilian Helicopter Services (BHS), under contract to Petrobras, suffered an obstacle strike and hard landing on the Sevan Brasil (SS-86), a Mobile Offshore Drilling Unit (MODU) off Brazil. None of the 21 occupants were injured in this accident, which was dramatically caught on video: Brazilian accident investigation agency CENPIA published their safety investigation report, in Portuguese only, on 3 November 2022, a disappointing 5½ years later. The Accident Flight The offshore helicopter had departed Cabo Frio for the Sevan Brasil under VFR, with two pilots, a cabin attendant and 18 passengers. CENIPA explain that the Aircraft Commander, who had flown 21,307 hours (3.294 on type) was sat in the left hand seat as an instructor & ‘Accredited Examiner’, and Pilot Monitoring (PM). In the right seat was a Pilot in Command Under Instruction (PICUS) who had 5,500 flying hours experience (253 on type) was Pilot Flying (PF). This was the flight crew’s third flight of the day. The Aircraft Commander had been PF for the first two offshore landings as the wind, and therefore the approach direction, favoured an approach best made by the left hand pilot. In fact the Aircraft Commander had made all landings in the previous three days they had flown together too. Sevan Brasil is a relatively novel circular hull MODU with a D23, t15.6 helideck, adequate for helicopters up to the size of the AW101, mounted at c 150 ft above sea level. The octagonal helideck is not mounted tangentially. CENPIA note the chevron marking that indicates the 210° Obstacle Free Sector (OFS) was incorrectly positioned. Though this is not relevant to this accident due to the chosen approach direction. More significantly, the helideck plate for the Sevan Brasil, which the crew consulted before departure, had… …no information regarding the positioning of the chevron, 150º and 210º sector orientations, helideck bow, wind limitations, relative wind, etc. This deficiency is of note because CENIPA also reveal that the flight was due to have been flown by another helicopter company, implying the crew would be less familiar with the installation and more dependent of the plate for their orientation. The investigators highlight that UK CAA CAP 437: Standards for offshore helicopter landing areas, probably the most widely referenced helideck standard, is far more explicit of the data that should be included. CENPA also highlight whip antennas and structure near the helideck were not marked in accordance with guidance in NORMAM 27 (the Brazilian helideck standard). However, CENPIA also commented that the guidance was not explicit about how far from the helideck these markings were necessary. The operator’s Operations Manual states that: The Aircraft Commander should use his judgment and experience in selecting what he considers to be the best profile. Factors such as: aircraft weight; wind speed; turbulence; size of helideck; elevation and orientation helideck; obstructions; available power margins; platform gas burner flames; etc., will influence the takeoff and landing decision-making. The Ops Manual goes on to list factors to consider such as Landing area location and wind direction; Wind strength; Experience level of each pilot; and Missed approach (go-around) profile. In this case it was decided that the PICUS, sat in the right...
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