The pilot reported that shortly after touchdown, he heard a noise followed by vibration from the nosewheel area. He subsequently lost directional control of the aircraft which came to rest beyond the left side of the runway. Post-flight inspection revealed that the nosewheel had collapsed, and that the propeller and left-wing tip were damaged. It appeared that the pilot overcontrolled with the elevator after the initial touchdown.

The pilot reported that during entry to the circuit at Rottnest he initially joined for a landing on runway 27 and he had lowered the landing gear early to help slow the aircraft down. During the circuit join the wind changed and he then manoeuvred for a landing on runway 09. He had to fit in with two other aircraft also manoeuvring for a landing on runway 09.

The pilot made a high approach for runway 09. Prior to the approach he had completed his downwind checks which included placing the landing gear lever in the down position and obtaining green indications. During the flare the landing gear warning horn sounded, and he applied full power, but it was too late to avoid a touchdown.

The pilot reported that a witnesses on the ground stated that the landing gear appeared to be in the down position but that it collapsed on landing.

An inspection of the aircraft at Rottnest Island indicated that there was no scuffing on the main wheel tyres as there would have been if the gear had rotated, on the ground, prior to retracting. The nosewheel doors were slightly open and the damage to them indicated that they were opening rather than closing.

There were a series of propeller strike marks for a distance of 350 ft along the runway. The depth of the marks indicated that the engine had been at a high-power setting and that the aircraft had flown parallel with the runway for most of the 350 ft.

An inspection of the landing gear, after recovery, did not disclose any evidence of collapse.

The evidence indicates that the gear was probably up when the warning horn sounded during the flare and it was in the process of extending when the aircraft touched down.

The grade one flying instructor was ferrying the kit helicopter to Mangalore where he planned to teach the owner/builder how to fly it.

About five minutes after departure, at 2000 feet, the pilot noticed an abnormal forward position for the cyclic in the cruise.  Fearing that there may be a problem with the cyclic control rigging, he elected to turn back to the nearest airfield which was Pakenham.  The cyclic control suddenly became very heavy and difficult to push to the left. However, for a short time it remained free to move in other directions.  Then, without pilot input, the helicopter rolled to the right.  The pilot was unable to prevent a right turn.  When the helicopter had turned onto south, the cyclic suddenly became loose and then stiff intermittently.

Fearing that something in the control system was about to fail completely, the pilot entered autorotation in an attempt to descend and land as quickly as possible.  During the descent, the helicopter pitched nose high then low severely, to the extent that the pilot thought the main rotor might cut off the tail boom.  He discovered that by maintaining rotor RPM and raising the collective lever when the nose pitched down, and lowering the collective when the nose pitched up, he was able to use the secondary effects of collective control to counteract some of the uncommanded pitching and rolling.

Nearing the ground the pilot was able to execute a flare to eliminate all forward speed.  At about ten feet AGL, the helicopter pitched nose up and rolled to the right.  The pilot closed the throttle and allowed the helicopter to sink, expecting it to roll over on the ground.  However, he managed to land firmly without damage.  While shutting down, the pilot noticed that the cyclic was stirring in circles by itself.

Subsequently, the helicopter was inspected by engineers.  No restriction of the cyclic control system was detected.

The helicopter owner subsequently advised the investigating CAA Airworthiness Surveyor that there was mention in the manufacturer's data that cyclic control problems may occur in hot conditions.  On the day of this incident the outside temperature was 34 degrees Celsius.

The investigation by the CAA has revealed that the friction adjustment of the slider ball (uniball) was temperature sensitive and caused binding of the cyclic control system. The CAA considered that the instructions provided by the kit helicopter manufacturer to address the cyclic binding problem were unacceptable.

The CAA was not made aware of the potentially hazardous problem during the application for the amateur built aircraft approval process.  Until improved, the Rotorway EXEC 90 does not comply with the Australian flight characteristics requirements for amateur built helicopters.

Significant Factors

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

1. The friction adjustment of the slider ball (uniball) was temperature sensitive.
2. Cyclic control binding resulted in significant loss of primary control in flight.
3. According to the CAA, manufacturer's instructions to rectify the potential cyclic control problem were inadequate.
4. Neither the helicopter manufacturer nor the Australian agent made the CAA aware of potential loss of cyclic control during the application for the amateur built aircraft approval.
5. The helicopter does not meet Australian design standards.
6. The pilot was unaware of a potential cyclic control problem until he encountered it in flight.

SAFETY ACTION

The CAA has withdrawn permits to fly the Rotorway EXEC 90 and will not issue a Certificate of Airworthiness to the helicopter type until convinced that the cyclic control system will operate in a satisfactory manner, with no mechanical degradation, and with a useful life, over a full range of temperatures including hot and cold soak likely to be encountered in normal Australian operations from minus 15 degrees Celsius to plus 45 degrees.

Whilst returning from the training area after a period of dual instruction, the engine suddenly stopped. Engine failure cockpit checks, which reportedly included selecting the alternate fuel tank, failed to restore power. The pilot declared an emergency and turned the aircraft toward a racecourse, the only available area for a forced landing. The aircraft touched down safely but the nose landing gear leg failed due to the action of heavy braking on soft earth.

Subsequent investigation determined there was no fuel in the right fuel tank, although the left tank contained about 48 litres. The engine started and ran normally when the left tank was selected. The instructor pilot had failed to adequately monitor the rate of fuel usage from the right tank during the flight and the engine consequently stopped due to fuel exhaustion.

On 10.1.95 VH-CZE was landed firmly at Coolangatta. The aircraft was being flown by a captain under training in the left seat. There was a training captain in the right seat and a first officer in the jump seat. After the landing, the purser, and the number 4 flight attendant (FA), both of whom were sitting in the forward cabin crew seats, reported sore backs/necks.

Because of these reports, the training captain requested engineering personnel to carry out a heavy landing check of the aircraft. The check revealed no damage, and the aircraft was returned to service. The training captain said he would not have considered a heavy landing check had the two cabin crew members not complained of sore backs/necks. A DFDR readout showed the maximum vertical G at touchdown was 2.022Gs. A normal landing is about 1.3Gs.

The crew reported that they joined the circuit on a visual downwind for runway 14 and were established on final approach at about 900 feet. The approach was being flown manually with the auto-throttle engaged. The aircraft was stabilised on the VASI and on approach speed. On short final the speed dropped a little, but auto-throttle compensated and picked it up. Closer in, the speed dropped again and at that point auto-throttle closed

(auto-throttle closes at 27 feet on the radar altimeter). Speed then dropped further but auto-throttle was now closed and therefore did not compensate. Both pilots pulled back on the control column, but the main gears touched down very firmly.

At touchdown, the aircraft was in an almost normal touchdown attitude. This was only the second auto-throttle landing (i.e. manually flown with auto-throttle engaged) that the flying pilot had done in the aircraft type. He had previous experience on the same aircraft type, with another operator, where this was not the practice. Since he had commenced flying with this operator, he had done six auto-throttle landings in the simulator and one in the aircraft, which was the landing prior to the landing at Coolangatta.

He believed he simply got caught with the speed low and then the auto-throttle closing at a critical stage.

Both pilots said conditions were more difficult on the previous landing and also for the next two landings after the Coolangatta landing, but the flying pilot made good auto-throttle landings on each of those occasions. The speed decay experienced on this landing was consistent with encountering mild windshear and this was evident in the DFDR readout.

Aviation medicine specialists were engaged in this investigation to assess the circumstances of the flight attendant injuries. An ergonomic assessment was made of the rear facing seats and their harnesses. The seats were assessed as providing no protection for vertical G forces. However, they also noted that the maximum G force involved in this occurrence should be tolerable with no ill effects if the correct seating posture is assumed. The restraint (harness) system installation for these seats was assessed as making optimum posture difficult to assume because of the position of the upper anchor points of the shoulder belts.

Factors

The following factors were considered relevant to the development of this occurrence:

1. The pilot flying lacked experience in the landing procedure using auto-throttle.
2. Late on final approach, the auto-throttle closed when airspeed was below target speed and reducing.
3. When the auto-throttle closed it was probably too late to correct the situation with power so both pilots pulled back on the control column, but this did not stop the aircraft touching down firmly.
4. Mild windshear contributed to the loss of airspeed.
5. The design of the forward flight attendant seats and restraint harness probably contributed to the minor injuries sustained by the flight attendants.

The pilot reported that during a practice engine off landing he flared the helicopter too high, and the rotor RPM decayed, resulting in a heavy landing. Some slight buckling of the tail boom, firewall, and left side panel was evident after the landing.

When climbing through FL120, the crew heard a loud bang followed by severe vibration. The Number 2 engine instruments indicated an EGT of 990 degrees and a vibration indication of 5 (most severe indication). The engine was shut down as per the checklist and the aircraft was returned for a safe landing. The engine was removed and failure of the Number 4 bearing identified as the cause of the malfunction.

The pilot reported that the aircraft engine lost power when he made a power adjustment whilst on final approach. The propeller feathered and the aircraft landed short of the runway on unprepared ground, incurring substantial damage. 

The aircraft was being used for parachute drops from 14,000ft. When the last parachutist left the aircraft, the pilot would place the aircraft in a steep spiralling descent. During this type of descent, the pilot was known to exceed the 60 degree angle of bank limits for the aircraft.

Low fuel states were reported as being used for the paradrops. It is probable that the fuel flow from the wing cells to the collector tank (18 litre capacity) was interrupted during the descent and air entered the system. The fuel pump was not designed to operate in other than a full collector tank. As a result it is likely that the fuel flow to the engine was interrupted, resulting in engine flame out.

Earlier in the afternoon the pilot had flown from Noosa to Toowoomba. After a short stay the pilot and his passengers boarded the aircraft a took off for the return journey. When the pilot selected the landing gear up it did not retract. He completed emergency checks and found that the hydraulic fluid level was low. The flight was continued to Maroochydore where engineering advice would be available.

Enroute the pilot contacted his maintenance engineer and following the discussion attempted to replenish the hydraulic fluid tank with engine oil. This was not successful.

The aircraft was landed with the gear retracted and sustained damage to the propeller and fuselage undersurface. All the occupants were uninjured.

Subsequent inspection revealed that the left main gear door actuator had separated allowing the hydraulic fluid to escape.

The pilot reported that he was spraying a potato crop and had 150 litres of chemical on board. Weather conditions were fine with a south easterly wind of three to five knots. He commenced his first run which was in a westerly direction and uphill.

At the end of the run, he switched off the spray and commenced a left climbing turn to avoid a nine metre high hedge with a house behind. The aircraft did not respond to control inputs and started to head for the hedge. The pilot managed to avoid the hedge but said the aircraft felt "mushy" and started to go down. The aircraft hit the ground and rolled over.

The pilot did not claim there was any fault with the engine. He had been flying a more powerful turbine powered helicopter until recently when he was endorsed on the Hughes 300. He had limited experience on the aircraft type at the time of the accident.