History of flight
The owner-pilot had used the Robinson R22 helicopter during the previous 14 days to transport himself and his assistant to several towns in the north-west of Western Australia in the conduct of his business. During the return journey to Geraldton, the pilot landed the helicopter the afternoon before the accident, at a relative's farm located near Binnu. At about 0850 WST on the morning of the accident, the helicopter departed from the farm to fly to Geraldton approximately 45 NM to the south. The pilot reported that about 10 mins after takeoff and when he had climbed to about 500 ft, the helicopter's engine oil temperature indication rose. There was no other cockpit indication of a potential malfunction. He suspected an electrical problem associated with the indicator due to previous occurrences but the indication also caused doubts in his mind as to whether he had properly secured the engine oil filler cap during the pre-flight inspection. Consequently, he decided to land to check. He reported that during the approach he saw the main power line and thought he was positioned such that he was clear of all power lines. The pilot reported that he did a reconnaissance of the proposed landing site by conducting a descending right turn from 500 ft. During the final approach, the helicopter struck a power line. The helicopter fell to the ground and was destroyed by the impact. There was no fire. The pilot sustained serious injuries and the passenger was fatally injured. The pilot reported that he never saw the wire and the last thing he recalled was feeling as though the helicopter had been "grabbed." He thought that the helicopter's airspeed was about 35 to 40 knots when it hit the wire.
The accident occurred approximately 5 km south of where the helicopter departed. The helicopter struck the upper conductor of a dual-conductor spur line running at approximate right angles to a main transmission power line located about 500 m to the south-west. The helicopter struck the spur line two bays from the main line about mid span at a height of about 8.4 m. The span distance was 205 m. Seven bays, approximately 1100 m, of conductor was pulled from the insulators and poles by the impact and the wire was dragged about 42 m during the accident. As well as itself breaking, the conductor broke several steel ties as it was pulled from the poles during the accident sequence. The steel ties secured the conductor to the insulators.
Observations at Geraldton and information provided by witnesses who were in the area at the time, indicated that the wind was a light southerly. There was some low-level cloud and the temperature was about 20 degrees C. There were no reported restrictions to inflight visibility.
The helicopter was a Robinson R22 Alpha, which is a two-place, single main rotor, single engine helicopter constructed primarily of metal and equipped with skid landing gear. The maximum gross weight of the helicopter is 1370 lbs. The approved grade of fuel for the helicopter was 100/130-grade aviation fuel. 100/130-grade aviation fuel is dye-coloured green. Automotive petrol (MOGAS) is coloured red.
The pilot reported that he suspected the high engine oil temperature indication was an electrical problem based on previous occurrences although the occurrences were not recorded in the aircraft's maintenance release or logbook. He also reported that there were no secondary indications, such as a fall in engine oil pressure or the illumination of a warning light. The Robinson R22 flight manual noted, "When a red warning light comes on, select the nearest safe landing area and make a normal landing as soon as practical." If an engine oil light illuminates, the flight manual noted that it, "indicates possible loss of engine power or oil pressure. Check the engine tach and oil pressure gauge. Continued operation without oil pressure may cause serious damage to the engine and engine failure could occur." The flight manual emergency procedures did not include any actions in response to an increasing engine oil temperature indication. The helicopter's manufacturer reported that it was considered unlikely that a missing engine oil filler cap would result in sufficient oil being lost to result in either low engine oil pressure or high engine oil temperature. Several maintenance organisations reported that a missing engine oil filler cap might lead to an indication of low oil pressure.
Baggage space is located under each of the seats. Each seat is equipped with a combined seat belt and inertia reel shoulder strap. The Robinson Helicopter flight manual requires the fitment of a placard in each baggage compartment, part of which states, "Avoid placing objects in compartment which could injure occupant if seat collapses during hard landing."
The daily inspection certification and aircraft time-in-service section of the helicopter's maintenance release had not been completed by the pilot during the 14 days prior to the accident although the helicopter had flown at least 20.9 hrs on 5 separate days. The pilot reported that he had conducted the required daily inspections but he intended entering the data on arrival at Geraldton. The maintenance release also revealed that a required 25 hourly servicing, oil change and set of inspections were due about 4 hours prior to the accident. The pilot reported that he had conducted the required inspections although they had not been certified in the maintenance release. He also reported that he had not completed the required oil change because he considered that it was not necessary. The engine manufacturer however required the oil to be changed every 25 hours and this periodicity was reflected in the maintenance release requirements. Several maintenance organisations confirmed that the oil change was required. Because the daily inspections had not been annotated as having been completed and required maintenance had not been completed, the helicopter was not being operated with a valid maintenance release. The helicopter had not been modified to use MOGAS and neither the helicopter's manufacturer nor the Civil Aviation Safety Authority (CASA) had approved the use of the fuel type in the accident helicopter. The pilot had also stowed a container of fuel in the cockpit, which was not in accordance with the Civil Aviation Regulations (CARs) pertaining to the carriage of dangerous goods.
The main wreckage came to rest about 69 m beyond where the helicopter impacted the power line. The damage to the aircraft was consistent with ground impact in a nose low, left bank attitude. The left seat squab supporting structure was found deformed from compression type loads generated in the accident sequence. Empty glass bottles were found under the passenger's seat. The nose low, left bank attitude of the aircraft resulted in the greater part of the impact forces being transferred through the fuselage to the left seat supporting structure and its occupant. An examination of wreckage did not revealed any pre-existing mechanical problem that may have contributed to the accident. Wreckage evidence and the pilot's report indicated that the engine was operating normally before the accident.
The left seat-belt anchor point, in the centre of the cabin seating structure, had failed. This failure liberated the inner belt anchor point from the aircraft structure and rendered the left occupant restraint system ineffective.
The fuel tanks had ruptured during the accident and consequently, no fuel remained in the fuel tanks. A plastic container, almost full of fuel, was found amongst the main wreckage. The fuel was red in colour and smelled of automotive fuel. The pilot confirmed that the container was filled with MOGAS and that he had it available for emergency purposes. He also advised that he had, on occasion, used MOGAS in the helicopter. Before the wreckage was removed from the site, a very small amount of fuel was found in the helicopter's fuel line. The fuel appeared to be automotive fuel. The pilot declined to comment to the investigation about whether or not he had fuelled the helicopter with MOGAS prior to the accident.
Evidence, including wire scrape marks on the landing skids and damage to the power line, appeared consistent with the helicopter hitting the wire in a nose low attitude and possibly at a relatively high speed.
The pilot had accumulated a total of about 290 hours flying experience, all in the Robinson R22. He gained his private helicopter pilot's licence 17 months prior to the accident and had flown about 26 hours in the 30 days prior to the accident.
The pilot had not received formal low flying training and was not authorised by CASA to operate the helicopter below the minimum altitudes prescribed in the CARs.
The flight-training documentation provided by the training school that conducted the pilot's helicopter licence training, highlighted the need for vigilance against wires when landing in unfamiliar areas. The prescribed procedure for landing in unfamiliar areas recommended that a high reconnaissance involving a series of checks (including checking for hazards such as power lines) be made at about 400 ft above ground level before making an approach. The procedure included, "Do not descend until you are sure that there are no powerlines that are going to interfere with your operations. Look for anything that uses electricity e.g. houses, sheds, pumps, lights etc. If necessary follow along a nearby powerline to ensure it does not go anywhere near your landing area. Look for stay wires, crossbeams, junction boxes etc. to indicate change of direction or spur lines".
The CARs also detailed the requirements pertaining to maintenance releases. A maintenance release ceases to be in force if a requirement or condition imposed in respect of the maintenance of the aircraft has not been complied with. Additionally, the regulations required the recording of total time-in-service of the aircraft on the completion of flying operations each day on the day.
The container of fuel was not packaged in accordance with dangerous goods requirements. The carriage of the fuel container in the helicopter cockpit was not, according to advice provided by the Civil Aviation Safety Authority, permitted by the CARs pertaining to dangerous goods.
The pilot reported that soon after takeoff the engine oil temperature increased. He also reported that he considered the indication was likely to be an electrical malfunction based on previous occurrences of a similar fault although such occurrences had not been recorded in the helicopter's maintenance documentation. Despite the lack of secondary indications to confirm the existence of a major problem, the indication was apparently sufficient to raise a doubt in his mind as to whether or not he had properly secured the engine oil filler cap. There was no reference in the helicopter's flight manual that indicated any immediate action was required. Although there was no information to indicate that an immediate landing was required, the pilot conducted a continuous turning descent to an immediate landing rather than performing the recommended reconnaissance procedure.
The recommended reconnaissance procedure in which the pilot had been trained for conducting landings in confined or unfamiliar areas, noted that a high reconnaissance should be made at about 400 ft above ground level before making an approach. The procedure included recommendations on how to assess the likelihood of a wire hazard. In this case, the terrain was flat and the spur line led to farm buildings that were 3 km from the junction with the main power line. There were few, if any, impediments to recognising the existence of the spur line. Consequently, it is likely that if the pilot had conducted the prescribed reconnaissance procedure, he would have had a higher probability of seeing the spur line. The pilot's perception that an immediate landing was required appeared to have diverted him from conducting the recommended reconnaissance procedure prior to making the final approach. These actions may have been a reflection of his low level of aviation and helicopter flying experience.
The stowage of the glass bottles in the baggage compartment under the passenger's seat would have significantly reduced the impact absorption qualities of the seat. It could not be determined, however, whether the stowage of the glass bottles was a factor in the passenger not surviving the accident.
The inconsistencies between the pilot's recollection of events immediately prior to the accident, and the wreckage evidence which indicated that the helicopter was in a nose-low attitude and possibly travelling at relatively high speed, could not be resolved.
During discussions between the ATSB and the manufacturer, Robinson Helicopters, it was revealed that the seat belt anchor points had been upgraded by a heat treatment process to strengthen the assembly. The manufacturer had previously highly recommended to all owners that, as the aircraft underwent the 2,000-hour rebuild; this unit be replaced with the upgraded part. This recommendation was not a mandatory requirement and consequently was not necessarily carried out on some aircraft.
Following the discussions with the ATSB, Robinson Helicopters has issued a Service Bulletin for the mandatory upgrade of the anchor point to the later heat-treated version.
|Date:||24 October 1999||Investigation status:||Completed|
|Time:||0900 hours WST|
|Location:||Binnu, 83 km N Geraldton, Aero.|
|State:||Western Australia||Occurrence type:||Wirestrike|
|Release date:||20 March 2001||Occurrence class:||Operational|
|Report status:||Final||Occurrence category:||Accident|
|Highest injury level:||Fatal|
|Aircraft manufacturer||Robinson Helicopter Co|
|Type of operation||Business|
|Damage to aircraft||Destroyed|
|Departure point||35 km W Binnu, WA|
|Departure time||0845 hours WST|
|Role||Class of licence||Hours on type||Hours total|