Collision with terrain

What happened

The pilot of a Bell 206 helicopter, registered VH-NKW, was tasked to drop equipment bags for seismic operations by using a magnetic bag runner connected to the helicopter by a 100 ft long-line.

The helicopter lifted off with seven bags loaded on the runner. During the flight of about 2 NM, the pilot observed that the bag lanyards became tangled. The pilot manoeuvred the bags onto the ground and using dual switches on the cyclic control, released the two solenoids to drop the first bag. The lanyard was tangled around the others and the released bag remained hanging and entangled with the other bags. The pilot then released the second bag and attempted to make the bags drop. He then repeated this for six bags and eventually one bag remained connected to the runner with the other bags entangled and hanging from it.

The pilot elected to land the helicopter to untangle the bags. He manoeuvred the helicopter backwards down the slope to land on a more suitable site. When about 10 ft above the ground, the pilot manoeuvred slightly further to the right however the long-line became fully extended. As the line pulled taut it came directly out the left side of the helicopter from under the centre of the left skid. This caused the helicopter to roll to the right.

The main rotor blade collided with the ground before the pilot reached the long-line release switch. The helicopter rolled over and came to rest inverted, resulting in substantial damage.

This incident demonstrates the importance of using equipment in accordance with established best practice. The operator advised that the bag runner is no longer to be used for bag layout operations; it is only to be used for bag retrieval/pick-up.

Aviation Short Investigations Bulletin - Issue 34

History of the flight

The aircraft had departed Bankstown for a dual instrument flight rules (IFR) training flight, including aerial work at Goulburn followed by two practice instrument landing system (ILS) approaches at Canberra, before returning to Bankstown.

After completion of the second ILS approach, the pilot was instructed to carry out a missed approach and climb to 7,000 ft.

As the aircraft was levelling in instrument meteorological conditions (IMC), the instructor noticed that engine Manifold Absolute Pressure (MAP) had reduced from 30 inches to 25 inches. He asked the pilot if he had adjusted the power and the pilot replied in the negative. At 1127 EST, the instructor advised Canberra Approach (APP) that the aircraft had experienced a loss of power. He reported that the aircraft was able to maintain 7,000 ft and confirmed that he wished to return to Canberra for landing. Air Traffic Control then instructed the pilot to turn the aircraft onto a southerly heading.

Between 10 and 15 seconds later, the aircraft occupants heard a loud thump that shook the aircraft, and the engine RPM reduced significantly. At 1128 the pilot advised APP that the engine had failed and requested that APP provide headings to the vicinity of Lake George. APP identified the aircraft on radar at a position 17 NM to the north-east of Canberra over the western shores of Lake George. APP then passed information to the pilot about an airfield near Bungendore as a possible landing area.

At 1129, the pilot advised that assistance was still required and confirmed that the aircraft was still in IMC. APP advised the pilot to disregard the previous vectoring instructions, indicated that a landing on the Federal Highway might be possible and instructed the pilot to turn onto a heading of 020 degrees.

At 1131, the pilot advised that the aircraft was descending through 4,200 ft. At 1132, APP requested that the pilot activate his emergency locator transmitter (ELT). The pilot then advised that the aircraft was still in IMC and passing 3,500 ft. APP advised that the aircraft was passing over the northern shores of Lake George and requested the pilot to turn the aircraft right to an easterly heading to avoid high terrain in the area. No reply was received.

Another aircraft, VH-DUP, was in the Goulburn area at this time and the pilot offered to relay a message to VH-SMA. APP requested the pilot of VH-DUP to listen out on 121.5 MHz to determine if an ELT had been activated. The pilot of VH-DUP advised that he was unable to make contact with VH-SMA and confirmed an ELT signal on 121.5 MHz.

The time of the accident was 1133. A rear-seat occupant, who was also a qualified pilot, later stated that he estimated that the aircraft broke through the cloud base below 300 ft above ground level (AGL).

An army helicopter was dispatched from Canberra at approximately 1155 and proceeded to the area of the last known position of VH-SMA. A second helicopter carrying a medical team was dispatched to the area at 1230.

Wreckage examination

Wreckage was distributed along a 49 m trail aligned approximately east. The aircraft had entered the timbered area on this track and had partially broken up as it descended through the trees. As the aircraft penetrated the timber, it struck and severed tree branches and trunks over 150 mm in diameter, starting 49.3 m and ending 28.5 m from the main wreckage, before coming to rest on a south-westerly heading against the trunk of a large tree approximately 1 m in diameter.

The main wreckage consisted of the fuselage, the fin, the right horizontal tailplane and most of both wings. The left horizontal tailplane had been torn off during the impact sequence. The empennage showed evidence of oil streaking, indicative of engine oil loss in flight. The fuselage had been almost completely destroyed by post-impact fire.

The engine and propeller remained attached to the fuselage. Inspection of the propeller indicated that the engine was not producing power at impact. The engine was basically intact and unaffected by fire. Both magnetos had separated from the engine. There were two holes in the top of the crankcase aligned with cylinders number 2 and 3. When the engine was turned over for examination, approximately 1 L of oil flowed out of the holes in the crankcase.

Significant factors

1. The engine failed due to a loss of effective lubrication. The reason for the loss could not be established beyond doubt.
2. The engine failure occurred in weather conditions that did not permit the pilot to carry out a visual forced landing onto favourable terrain.
3. The approach controller was unable to vector the aircraft to an obstruction-free landing site due to equipment and time limitations.

The aircraft was engaged in a flight from Proserpine to Bankstown with an intermediate stop at Coolangatta. On arrival at Coolangatta the aircraft was refuelled and the pilot attended the Briefing Office, where he was provided with copies of the relevant weather forecasts for the remaining part of the flight. These forecasts indicated a strong west-south-westerly airflow over northern New South Wales, with considerable low level cloud to the west of the mountains but only scattered stratocumulus or cumulus up to 6,000 feet to the east and over the coast. The freezing level was expected to be between 4,000 and 7,000 feet above mean sea level, and moderate icing was forecast in cloud above that level. A SIGMET (forecast of significant weather which may affect aircraft safety) was current, indicating occasional severe turbulence existed below 12,000 feet to the east of the mountains.

The pilot held a current Class 3 Instrument Rating, which entitled him to make the flight under the Instrument Flight Rules (IFR). The aircraft was also approved for IFR operations, but not for flight in known or forecast icing conditions, as it was not equipped with suitable airframe de-icing equipment.The pilot elected to conduct the flight in accordance with the visual meteorological conditions at night (Night VMC) procedures.He submitted a flight plan which indicated he intended to track along the coast to Taree, then inland via Craven, Singleton and Mt. McQuaid in order to avoid controlled and military restricted areas surrounding Williamtown.

After departing Coolangatta the flight proceeded without recorded incident to Taree. At this point the pilot reported to Sydney Flight Service Centre that he was cruising at 8000 feet and estimating overhead Singleton at 1930 hours EST. At the suggestion of Flight Service and with the agreement of the pilot, Flight Service and Sydney Air Traffic Control then began to co-ordinate a clearance to allow the aircraft to continue to track, more directly, via the coast and transit the Williamtown military areas, however this clearance was delayed because of uncertainty regarding the amount of cloud and general weather conditions to the south of Williamtown. Some 8 minutes after passing Taree the pilot advised that he would continue on his planned track rather than hold to the north of Williamtown pending the issuing of a clearance. He subsequently reported when passing the Craven position, and advised that the aircraft was experiencing "considerable turbulence now and quite a lot of downdraught". Five minutes later, at 1924 hours EST, the pilot reported that the aircraft had entered cloud. He requested a clearance to climb to 10,000 feet and shortly afterwards advised that the primary flight instruments, i.e. the artificial horizon and the gyroscopically controlled direction indicator had failed.

Search and Rescue procedures were initiated and at 1928 hours the aircraft was identified by radar. At this time the aircraft was near the Barrington Tops, some 58 km north of Singleton, and about 40 km northwest of the planned track. This information was relayed to the pilot, who advised that he was having difficulty in climbing to 8,500 feet. At 1934 hours he indicated that the aircraft was no longer in cloud, however it had accumulated "a fair amount of ice". He continued to report strong turbulence and further ice accretion, and indicated that the aircraft was descending rapidly. The last recorded transmission from the aircraft was at 1939 hours, when the pilot advised the aircraft was at five thousand feet. Radar contact with the aircraft was also lost at this time.

An extensive air and ground search was immediately commenced and continued for 10 days without success. Subsequently the search has been reactivated on a number of occasions in response to reports of wreckage being sighted. However, no trace of the aircraft or its occupants has been found.

What happened

On 23 May 2014, at about 0855 Eastern Standard Time, a Bell 412 helicopter, registered VH-ESD, conducted a winching operation about 72 km WNW of Townsville, Queensland. The crew consisted of a pilot, an air crew officer (ACO), a rescue crew officer (RCO), a paramedic and a doctor.

The pilot established the helicopter in a hover about 100 ft above the ground facing down the slope. The ACO directed the pilot to manoeuvre the helicopter to perform the operation and remain clear of all obstacles. The doctor and RCO were winched down to the site together, and subsequently the paramedic was lowered. The pilot conducted an orbit before returning to winch the stretcher and rescue equipment down.

The pilot and ACO then departed and after about 15 minutes, returned to commence the winch recovery. The ACO directed the pilot to manoeuvre the helicopter and winched up the doctor and the stretcher. The ACO handed the visual reference over to the pilot, while his attention was focused on securing the stretcher inside the cabin.

About 1 minute later, the ACO returned to the door and observed that the helicopter had drifted back and left and he immediately directed the pilot to manoeuvre up and to the right, however the tail rotor collided with some foliage. The ACO advised the pilot. The pilot had not detected any strike, there were no abnormal indications or vibrations and the helicopter was operating normally.

The RCO and paramedic were then winched into the helicopter and the ACO returned to the front seat. After landing, the pilot observed some ripples on the tail rotor blades. 

This incident highlights to helicopter pilots the importance maintaining a good reference point when operating in confined areas.

Aviation Short Investigations Bulletin - Issue 33

What happened

On 23 May 2014, at about 1100 Eastern Standard Time, the pilot of a Robinson R22 helicopter, registered VH-WDB, conducted a local flight on a property about 90 km north of Bourke, New South Wales. The pilot flew the helicopter to a cleared landing area adjacent to a stock yard. From about 600 ft above ground level (AGL), he commenced the descent to the landing site, aiming to approach quietly and slowly to minimise disturbance to stock grazing nearby. When at about 9-15 ft AGL, he commenced a left turn into a light breeze, then at his 11 o’clock position, and entered the hover.

As the helicopter turned left, the pilot felt a violent shudder through the cyclic control. The pilot reported that the helicopter continued to yaw and he applied opposite pedal in attempt to counteract the yaw, however the pedal was ineffective and the yaw accelerated. The pilot rolled the throttle off, moved the cyclic forward and lowered the collective. As the helicopter descended rapidly, the pilot then raised the collective to cushion the landing. The right skid touched down first and the helicopter rolled to the right, coming to rest on the right side.

No aircraft unserviceabilities, including in the tail rotor control system were found other than those sustained in the accident. The drive belts were found intact and had moved forward one groove on the upper sheave consistent with a power-on main rotor strike.

The helicopter was substantially damaged, and the pilot was uninjured.

Aviation Short Investigations Bulletin - Issue 33

What happened

On 19 May 2014, at about 0705 Eastern Standard Time, a Kavanagh Balloons D-84, registered VH-YPI, departed from a site 1.5 km west of Canowindra Aeroplane Landing Area (ALA), New South Wales, on a training flight, with an instructor and student pilot on board. The flight was conducted in visual meteorological conditions.

During the flight the student conducted a number of approaches to land, which were levelled out with intentional overshoot just above ground level. About 50 minutes into the flight, possible landing areas were selected. The balloon flew low and level and the landing area that favoured the surface wind conditions was selected. A normal approach was made using windy landing procedures, in about a 10 kt wind. The balloon flew over a line of trees on the eastern side of the landing area and descended.

At about 0805 and 10 km south-south-west of Canowindra ALA, and about 30 ft above the ground the student indicated to the instructor that they would be landing and turned out the pilot lights. At about 6 ft above the ground the student pulled the smart vent to land. The basket contacted the ground, and the instructor was thrown forward and out of the basket while the student remained in the basket. The basket hit the instructor who was lying on the ground and the basket was dragged over him. The student continued to vent the balloon and it stopped a further 20 m downwind.

The instructor was seriously injured and transported to hospital, the student pilot was uninjured, and the balloon was not damaged.

The accident highlights that it is important for everyone in the balloon basket to assume and maintain the landing position and to hold on tight until the balloon fully stops.

Aviaiton Short Investigations Bulletin - Issue 37

On 12 December 2013, a Sikorsky S-76C helicopter, registered 9M-STE, collided with the sea during bad weather off the Bintulu coast, Malaysia.  Both pilots and six oil platform workers were rescued. An investigation into the circumstances of the accident is being conducted by the Malaysian Air Accident Investigation Board (MAAIB).

The MAAIB requested assistance from the Australian Transport Safety Bureau (ATSB) in the download and analysis of the helicopter’s cockpit voice recorder (CVR).

To facilitate this support and to provide the appropriate protections for the CVR information, the ATSB appointed an accredited representative in accordance with paragraph 5.23 of ICAO Annex 13 and commenced an investigation under the Australian Transport Safety Investigation Act 2003.

The CVR unit from the accident helicopter, a Universal Avionics Systems Corporation model CVR-30A, was brought to the ATSB’s Canberra technical facilities by two Malaysian air safety investigators on 20 May 2014. Subsequent disassembly showed evidence of water ingress into the recorder’s crash-protected module. Following cleaning and drying, a download in accordance with the CVR manufacturer’s specifications, was attempted. However the download was unsuccessful.

Following a dialogue with the CVR manufacturer a supplementary procedure for the data recovery was developed and agreed to by all parties. The supplementary procedure involved removal and download of all 66 memory devices from the module that was involved in the accident. The data from each device was then written to new memory devices, which were then mounted on a new memory module.

A full download of the recorded CVR information was made on the 14 October 2014 and the MAAIB was immediately advised of the successful recovery of the information. The digital audio files relating to each of the four channels were then provided to the MAAIB via secure file transfer.

The MAAIB is responsible for releasing the final investigation report regarding this accident.

The MAAIB can be contacted via: www.mot.gov.my/en/aviation/air-incident-investigation

What happened

On 13 May 2014, the pilot of a Robinson R22 helicopter, registered VH-HEP, was conducting aerial mustering operations on a property about 40 km north-east of Hughenden, Queensland.

As the pilot was mustering a herd of cattle, a number of cattle retreated to a protected area beneath trees. The pilot descended in what appeared to be a clear area adjacent to the trees in an attempt to keep the cattle moving, but as the aircraft descended the main rotor blade struck a dead tree.

The pilot was immediately aware of the blade strike, and could feel vibration through the helicopter cyclic control. Concerned about the extent of damage to the helicopter and possible loss of control, the pilot elected to make a controlled descent to the ground immediately beneath. A fire ignited in the grass beneath the engine behind the cockpit area after the helicopter settled on the ground. The pilot was able to retreat to a safe area and was uninjured, but the fire grew rapidly and destroyed the helicopter.

This incident highlights the importance of continuous awareness of obstacles during aerial mustering operations, particularly when manoeuvring in relatively confined areas. Although the pilot had little choice on this occasion, this incident serves as a reminder of the fire hazard associated with landing in long grass.

Aviation Short Investigations Bulletin - Issue 34

Safety summary

What happened

On 27 March 2014 the pilot of a Robinson R22 helicopter, registered VH-HRX, departed from Mullapunyah station, Northern Territory, for a short flight to the north-west. About 10 minutes after departure the pilot radioed that the drive v‑belts had failed and the station owner, in another R22, saw the helicopter enter a steep descent.

Soon after, the station owner found the helicopter complete and upright in a relatively clear area. The pilot of VH-HRX, who was laying a few metres from the helicopter, had sustained a serious head injury. The station owner tended the casualty and alerted emergency services at Borroloola of the accident, as well as personnel at the station homestead. Station personnel accessed the accident site over the rough terrain and started to transport the injured pilot on the back of a utility vehicle. The casualty was later transferred to a Bell 206 Jetranger helicopter for transfer to Macarthur River Mine. An aeromedical service then transported the injured pilot to Darwin where he was hospitalised for a number of weeks.

What the ATSB found

During the initial engine start/clutch engagement process following an extended period of static belt stretching, one or both rotor drive v-belts were displaced on the lower sheave with consequent increase in v-belt slack. Although the pilot, who was not qualified to conduct such maintenance, adjusted the clutch actuator to correct the excessive v‑belt slack, the v-belt displacement went undetected. While being operated in that abnormal configuration, one of the belts weakened and failed with consequent failure of the remaining belt, loss of drive to the rotors, and a forced landing.

Although Robinson Helicopter Company Safety Notice SN-33 provided guidance to pilots on how to stretch new v-belts statically, it did not specifically warn pilots that this process can increase the risk of belt displacement during the subsequent start.

Safety message

This accident highlights that in addition to having a good working knowledge of Robinson Helicopter Company Safety Notice SN-33, R22 pilots and engineers should be especially aware that, if the rotors do not turn within 5 seconds after clutch engagement, it is critical to perform the shutdown procedure and check the slack and position of the v-belts on both the lower and upper sheaves, before flight.

Pilots and operators of helicopters should also consider the residual risk of their operation and the benefit of occupants wearing helmets to reduce the risk of head injury in the event of an emergency landing.

What happened

On 22 March 2014, the pilot of a Robinson R22 helicopter, registered VH-YPS, was conducting aerial mustering on a property about 28 km east of Fitzroy Crossing aerodrome, Western Australia. The pilot had refuelled the helicopter from a jerry can and then secured the empty can in the passenger seat using the seatbelt.

At about 1530 Western Standard Time, the pilot manoeuvred the helicopter to the rear of a mob of cattle. From about 300 ft above ground level (AGL), the pilot conducted a balanced descending turn.

When at about 10 ft AGL, he applied right pedal and as he raised collective to climb away, a gust of wind blew through the left door opening and dislodged the jerry can from the seatbelt. The can became wedged between the seat and the cyclic control. The pilot applied forward cyclic, and the nose of the helicopter lowered. As he then attempted to apply aft cyclic to raise the nose, he realised the cyclic was jammed. With the low nose attitude and minimal height above the ground, the pilot used collective in an attempt to flare the helicopter. The front of the landing skids collided with the ground and the helicopter rotated forwards. The main rotor blades chopped through the tail boom and the helicopter continued rotating forwards and bounced back up to about 50 ft AGL before coming to rest inverted.

The pilot reported that the impact dislodged the top of the front dashboard and struck his helmet. He was uninjured and the helicopter sustained substantial damage.

This incident highlights the importance of ensuring all items are securely stowed. It also provides a timely reminder to pilots of the benefits of safety equipment such as a helmet.

Aviation Short Investigations Bulletin - Issue 30