Loss of control

An emotionally disturbed young woman was allowed to board the aircraft as the sole passenger for the 25-minute flight. At top of climb, the passenger attacked the pilot and made an attempt to exit through the pilot's side window. In the process, she disturbed the aircraft and engine controls. The aircraft descended out of control from 4,500 ft and after pushing the passenger out of the cockpit, the pilot regained control by 3,000 ft. After being threatened by the pilot, the passenger remained subdued for some time. However, approaching Bundaberg, she again became agitated and harassed the pilot. The aircraft landed safely.

Resort staff allowed the passenger to board the aircraft unescorted despite the availability of suitable staff. The passenger had been "playing up" all weekend had caused problems at the resort.

The pilot said that he had intended to fly practice circuits in the tailwheel aircraft. During the landing roll of his first circuit, he lost directional control at about 25 to 30 knots indicated airspeed. After yawing first left then right, the aircraft entered a ground loop to the left at about 20 to 25 knots. The right-wing tip and right tail plane made contact with the ground.

The aircraft was taxied back to the hangar.

The passenger, who was an experienced instructor but was on board as a passenger, indicated that the pilot had made inappropriate control inputs following touchdown. This led directly to a loss of control. An intercommunication system was not fitted in this aircraft.

The student helicopter pilot elected to conduct an unsupervised hover practice at Casey Airfield.  His total helicopter experience was 27 hours dual and seven hours solo, all in his privately owned Rotorway EXEC 90.  The terrain over which the helicopter was hovering was level ground covered by grass about half a metre high.  The wind was calm and visibility excellent.  The pilot advised that while trying to land, the front of the right skid touched the ground first and the helicopter rolled over onto its side.  Damage sustained by the helicopter was consistent with a rollover accident.  The rollover probably occurred as the helicopter drifted sideways with the landing skids in the grass.

During wreckage inspection of VH-COC it was discovered that the collective scissor link block was off its mount and that the nuts had been pulled off the two 3/16 bolts which attach the block to its mount.  There was concern that had the block pulled free before impact, loss of collective control would have occurred, probably resulting in sudden flat pitch on both main rotor blades.  Such loss of control in the hover probably would have caused the helicopter to be slammed onto the ground with more resultant damage than occurred in this rollover accident.

Another wrecked Rotorway EXEC 90, VH-YCP, was examined for comparison. Its scissor link block was still attached but score marks and fretting under the bolt heads were evidence that the block had not been securely attached to the airframe mount.  Similar evidence of fretting was subsequently found on VH-COC.  On both helicopters the airframe mounts were not flat surfaces. Also, both mounts were coated with paint which could be detrimental to a close tolerance fit.  In contrast, the base of the scissor link block was a machined flat surface.  When one end of the block was attached with a bolt, the other end of the block was proud of the steel mounting plate by 0.020 inches.

It was discovered that the Civil Aviation Authority (CAA) had required the collective scissor link attachment bracket, originally supplied by the manufacturer, to be replaced by the block of aluminium.  A bracket might flex enough during installation to achieve a flush fit with the mounting plate, whereas the aluminium block was inflexible.

Further inspection of Rotorway helicopters discovered that there was no airframe down stop for the collective lever in the cockpit and that the mechanical advantage between the collective lever and the scissor link was 24 to 1. Pushing down on the collective lever placed the two 3/16 bolts in tension.  Several 3/16 aircraft bolts were tested in tension to destruction. On average the nuts pulled off the bolts at 2714 ft/lbs.  In training, particularly during practise autorotations, it is normal for the pilot (occasionally for both the pilot under instruction plus the instructor) to push down on the collective to ensure flat pitch.  The combination of bolts under tension and the non flush fit of the blocks on VH-COC and VH-YCP had caused the blocks to move/work in the past and in time could have caused the bolts to fail.

Significant Factors

The following factors were considered relevant to the development of the accident:

1. The student pilot conducted an unauthorised solo flight.
2. The pilot probably inadvertently allowed the landing skids to drag through long grass as the helicopter drifted sideways in the hover.

Safety Action

The CAA was immediately informed of the Bureau's findings and concern about the attachment of the collective scissor link block to the airframe.  A CAA Airworthiness Surveyor inspected VH-YCP. The Australian agent for the Rotorway kit helicopter was advised verbally of the findings.  The CAA approved Australian Rotorway EXEC 90 test pilot, and the CAA test pilot were advised of the findings as soon as possible.

Since this accident there has been a Rotorway EXEC 90 incident in which cyclic control became marginal in flight, resulting in a very unsafe condition. This incident exposed that the aircraft type did not comply with the flight characteristics requirements for an amateur built helicopter in Australia.  It was found that the friction and adjustment of the slider ball (uniball) was temperature sensitive and had caused binding of the cyclic control system. The instructions provided by the manufacturer to address cyclic binding were not acceptable to the CAA.

The CAA was not made aware of the potential cyclic problem during the application for the amateur built aircraft approval process.  Accordingly, the CAA has withdrawn Permits to Fly, and a Certificate of Airworthiness will not be issued for any helicopter of this type until the matter of the cyclic control is resolved.

Witnesses reported seeing the helicopter land in the corner of a fenced paddock. A short time later the helicopter took off again but after climbing to about three metres above the ground, it began rotating and gyrating erratically, contacting the ground a number of times. It came to rest in an upright position but with the tail boom severed and damage to the main rotor assembly and gear box.

The pilot reported that he had recently recovered from a viral complaint which was characterised by severe coughing bouts but had been free of these symptoms for a few weeks. As he flew over the area of the accident, however, he had experienced the incipient stages of a coughing fit, so he landed the helicopter, shut the engine down, and walked around for a short time until the symptoms disappeared. He then reboarded the helicopter to continue the flight but shortly after lift-off was overcome by a severe coughing fit. This caused him to partially lose control of the helicopter, and it contacted either the fence or the ground.

The helicopter was tracking coastal at about 500 feet AMSL when the pilot saw a crocodile on a riverbank and commenced a descent to enable photographs to be taken. He made a right turn to position the helicopter into wind while descending to a height of about 100 feet and decelerating to 10-20 knots.

As the helicopter came out of the turn the pilot applied normal up collective control and left anti-torque pedal to regain level flight which was immediately accompanied by a severe vibration. The helicopter began to rotate rapidly to the right and the pilot applied full left pedal, but with no response, the feel on the pedals being as if they were detached from the tail rotor system.

The pilot lowered the collective and applied forward cyclic in an attempt to control the rotation and vibration. Although the rotation rate slowed, the helicopter rotated through another 2-3 turns and descended to about 30 feet above the sea. The pilot realising that he would be unable to effect a successful recovery, landed the helicopter in the water with a forward speed of about 10-20 knots in a tail low attitude while still rotating to the right.

The helicopter rolled inverted and floated upside down for 3-4 minutes. All occupants evacuated the helicopter and swam ashore. The helicopter sank, but after a while it resurfaced then floated out to sea on the tide and was recovered the next day. The tail boom was found to have been severed behind the horizontal stabiliser, the vertical fin, tail rotor gearbox and tail rotor being lost in the sea.

Subsequent investigation revealed that the tail rotor drive forward short shaft had failed due to torsional overload. The severed tail boom, when matched to a serviceable helicopter of the same type, showed that the damage and impact marks were found to align with the tail rotor blades. The tail rotor drive long shaft had only slight impact damage and had uncoupled intact off the splines at the tail rotor gearbox, indicating that a main rotor blade impact had not caused the tail boom to fail.

The tail boom was severed by a direct strike from a tail rotor blade under power, which then caused the tail rotor drive short shaft to fail under load. It was not possible to determine the reason why the tail rotor blade struck the tail boom.

On 3 October 2014, at about 0900 Western Standard Time, a Jabiru J230 aircraft, registered 24-7491, departed Cape Leveque for Broome, Western Australia, with a pilot and one passenger on board. When at about 5 NM from Broome Airport, an air traffic controller cleared the aircraft to join a right circuit for runway 28. The pilot reported that the approach and landing were normal and the aircraft touched down on runway 28 just beyond the threshold.

During the landing roll, the pilot was focused on looking for the correct taxiway to exit the runway for the itinerant parking bay. The aircraft was decelerating normally and the pilot did not apply brakes due to the length of runway remaining. The pilot detected the right wing rising slightly, possibly due to a crosswind. He then looked straight ahead and realised that the aircraft had veered off the runway centreline to the left. He applied right rudder in an attempt to return to the centre of the runway, but the aircraft continued towards the edge of the runway and taxiway A. He sighted a grass area and a drainage ditch ahead just off the runway which he wanted to avoid, along with a Fokker 100 aircraft that was stationary on taxiway A at the holding point for runway 28. The pilot elected to apply full left rudder to turn the aircraft around and remain on the sealed area.

The Jabiru aircraft’s propeller and right wingtip struck the ground and the aircraft came to rest upright and facing in the opposite direction to the landing and about 20 m from the Fokker 100. The pilot and passenger were uninjured.

Aviaiton Short Investigations Bulletin - Issue 37

On 3 July 2014, a Piper Aircraft Corp PA-28-161, registered VH-TEK, was returning from the training area via the 2RN reporting point to Bankstown Airport, New South Wales. The student pilot was the only person on board. The flight was conducted in visual meteorological conditions.

The student tracked from the 2RN reporting point and joined downwind for a touch-and-go landing on runway 29L. The student turned onto base and then final and the Bankstown tower gave the student a clearance to conduct a touch-and-go clearance. The student reported that the approach and landing were normal. As soon as the student felt the aircraft wheels were on the ground, he reached down to the flap lever and selected the flaps to the retracted position.

The aircraft veered slightly to the right and then quickly to the left, departing the runway and onto the grass strip. The student regained control of the aircraft and informed the tower of what happened, reporting that he did not require assistance. The student then taxied onto taxiway B, between taxiway B4 and B3, passing about 20 metres in front of a taxiing Cessna 150. TEK taxied to the flying school without further incident. The student pilot was uninjured, and the aircraft was not damaged.

Aviation Short Investigations Bulletin - Issue 38

On 10 May 2014, an accredited Cirrus salesman conducted a sales demonstration flight of a Cirrus SR22 aircraft, registered N802DK, in the local training area, from Bankstown Airport, New South Wales, with a pilot (and potential aircraft buyer) seated in the front left seat and one passenger on board. At about 1330 Eastern Standard Time, the aircraft departed Bankstown and the salesman, as pilot in command (PIC) elected to track towards Katoomba at about 6,000 ft above mean sea level.

After demonstrating a series of turns and a straight and level stall, the PIC selected 50% flap, rolled the aircraft into a left turn at about 25° angle of bank, reduced the power to idle, and raised the nose of the aircraft. The right wing dropped rapidly, and the aircraft entered a spin to the right. When about 2,000 ft above ground level, the PIC was unsure whether he then had enough height remaining to recover control of the aircraft, and elected to deploy the aircraft’s parachute. The rocket fired, the aircraft initially pitched up slightly and then as the parachute deployed, the aircraft pitched down rapidly into a nose low attitude. About 6 seconds after the rocket fired, the right snub line of the parachute released, followed by the left snub line, which then established the aircraft in a wings level attitude.

The aircraft narrowly avoided powerlines, collided with branches of a tree, and came to rest on a fence in the garden of a residential dwelling.

This incident provides a reminder to pilots to know your own limitations and those of the aircraft.

Aviation Short Investigations Bulletin - Issue 33

On 15 January 2014, the pilot of a Piper PA‑28 aircraft, registered VH‑HVX, was undergoing a Commercial Pilot Licence test flight with a testing officer on board. At about 1500 Eastern Daylight-savings Time, the aircraft landed at Orange Airport, New South Wales. The aircraft had encountered moderate turbulence during the flight from Bankstown and the pilot reported a slight overshoot on landing at Orange due to fluctuating wind conditions.

During the time on the ground, the pilot observed the wind varying from an easterly to a westerly direction and the speed fluctuating from 0 to about 15 kt. The temperature at Orange was about 33 ºC, and the aerodrome elevation was 3,115 ft. The pilot had calculated the density altitude at Orange to be about 5,725 ft.

At about 1530, the pilot observed the wind to be from 110º at about 10-15 kt and configured the aircraft for a short field take-off from runway 11, selecting two stages of flaps. During the take-off run, the pilot and testing officer observed the aircraft performing normally and the pilot rotated the aircraft at about 55-60 kt indicated airspeed (IAS). The pilot then established the aircraft in an attitude to achieve a best angle-of-climb speed of about 72 kt IAS. The pilot reported that the stall warning horn sounded momentarily during the take-off due to turbulence.

When at about 50 ft above ground level (AGL) and about 65-70 kt IAS, the testing officer reduced the engine power to idle and stated “simulated engine failure”. The pilot immediately lowered the nose of the aircraft in an attempt to increase the airspeed and selected the third stage of flaps. At about 10 ft AGL, the pilot reported the aircraft was sinking and flared the aircraft for landing. However, the aircraft continued to sink and landed heavily. The pilots reported that the stall warning did not sound during the descent and that a shift in the wind direction was the most likely cause of the accident.

This incident highlights the critical importance of considering local conditions such as wind, elevation and temperature, as well as the inherent risks of conducting simulated engine failure at low altitude.

Aviation Short Investigation Bulletin - Issue 28 

On 7 December 2013, the pilot of a Cessna 182 aircraft, registered VH-LMA, departed Albury, New South Wales on a private flight to the Tyabb aeroplane landing area (ALA), Victoria. The flight was being conducted under the instrument flight rules (IFR), and on board were the pilot and one passenger.

After the aircraft had left controlled airspace and with about 6 NM to run, the pilot levelled the aircraft at 1,100 ft to prepare to join the circuit on an extended left base leg for runway 17.

When on final approach, he checked the secondary windsock and noted the wind was predominantly crosswind from the right, gusting around 5-10 knots. With the final stage of flap selected, the aircraft touched down on the main wheels about 20-30 metres past the runway threshold, close to the centreline. The pilot estimated the aircraft speed at touchdown was about 65 knots. During the landing roll, he applied a small amount of right aileron to counter the crosswind.

When the aircraft had slowed he began to apply the brakes. At about the same time, a gust of wind pushed the aircraft to the left. The pilot applied right rudder in an attempt to steer the aircraft back to the centreline, but stated the aircraft pulled to the left and felt like the left brake had locked. The aircraft rapidly decelerated, and continued along a path through the wet grass a few metres to the left of the sealed runway. As it stopped, the aircraft nosed forward, and then tipped over onto its back.

The pilot and his passenger were hanging upside down in their seatbelts. A person who had been waiting for the aircraft to arrive assisted the young passenger and then the pilot. The pilot and passenger sustained minor injuries, and the aircraft was substantially damaged.

A search of the ATSB database for fixed wing, private operation accidents, 2004 to 2013 found the landing phase accounted for 33% of all accidents. The take-off and initial climb phases together accounted for 25% of accidents from this group.

Aviation Short Investigations Bulletin - Issue 29