The pilot of a Cessna 206 reported hearing an unusual noise as the nose wheel was lowered during the landing sequence. As a precaution, he increased back-pressure on the control column to keep the nose wheel off the ground for as long as possible during the landing roll. However, the nose wheel assembly subsequently collapsed, resulting in substantial damage to the propeller and engine cowling.

An inspection of the failed nose gear assembly by a LAME revealed no pre-existing defect with the unit. This occurrence was not investigated by BASI. No reason was given for the failure of the landing gear.

The pilot of a Grob 115 aircraft was conducting a series of circuits after returning from a solo flight to the training area. During the second touch and go the pilot lost directional control. The aircraft veered left and departed the runway, incurring substantial damage as it passed through a ditch. The pilot was uninjured and vacated the aircraft without assistance.

An Airbus A320 taxied at Adelaide and the crew requested an airways clearance to Brisbane. Air traffic control issued the crew with a clearance to Brisbane via UVUPU (064 AD VOR 181NM) and planned route to cruise at FL370 with a runway 23 RADAR 3 departure. This clearance was correctly read back by the crew. However, the departures flight progress strip (FPS) for this flight had been incorrectly annotated with an UVUPU 2 standard instrument departure (SID) instead of a standard radar departure (SRD) RADAR 3.

When the crew reported ready for take-off the approach east (APPE) radar controller issued an "unrestricted" instruction to the aerodrome controller (ADC). The ADC cleared the aircraft for take-off without assigning a radar heading. The flight crew did not query this instruction and the A320 became airborne, the crew electing to maintain runway heading. The crew contacted APPE and reported "tracking runway heading, climbing to FL370 left 2,800". They requested approval to track direct to UVUPU which was approved by the controller. Believing the aircraft to be tracking via the SID, a discussion between the pilot and APPE then revealed that the pilot understood that he had been cleared on a RADAR 3 Departure, while the controller understood that the aircraft was tracking via the UVUPU 2 SID.

There were no traffic conflictions. The investigation revealed that there were two contributing factors in this occurrence. The aircraft callsign had been changed on the FPS and the APPE controller was concerned that the SSR code on the strip may have been entered incorrectly. While confirming this detail he was distracted and annotated the FPS with an incorrect clearance. The technique of writing the clearance on the FPS prior to the issuance was considered a significant factor. The controller had already written UVUPU 2 on the FPS and when he was distracted during the issuing of the clearance, he had made an incorrect assumption, which had been influenced by the clearance already written on the FPS. The pilot in command had been issued with a standard radar departure clearance which required an assigned heading to be issued by the ADC with the take-off clearance. When the crew received the take-off clearance without the assigned heading, they should have immediately queried the instruction.

However, they elected to take-off and maintain runway heading. This action was consistent with the SID procedure. On first contact with APPE, the crew did not specifically mention that they did not have a heading to fly, and the controller incorrectly assumed that they were departing on a SID, in accordance with the annotation on the FPS. There were explicit instructions in the Aeronautical Information Publication, which detailed the requirements to be followed when departing on a SRD. The controller was required to assign a heading prior to issuing the take-off clearance and the pilot was required to read-back that heading. Considering that air traffic control had two clearances current for the departure, the last safety defence was the assigned heading in the standard radar departure. Had the crew queried that no heading had been assigned for their departure, APPE would have immediately queried the requirement

The flying instructor stated that he was conducting a trial instructional flight in conjunction with visiting his property with the student. A few minutes after landing, he performed a vertical take-off into an estimated 10 kt northerly wind. Engine RPM was close to the desired 2,700. The helicopter climbed vertically using 28 inches of manifold air pressure, leaving about 1.5 inches in reserve. It cleared the tops of the trees at about 40 ft AGL. The instructor then lowered the nose slightly to gain airspeed. As airspeed increased to about 10 kts the helicopter climbed to about 45 ft AGL.

The instructor then allowed the helicopter to accelerate without increasing power when suddenly, after about 30 metres, the engine RPM commenced to decay. He immediately applied full throttle and lowered the collective slightly but RPM continued to decay and the helicopter lost height. He immediately turned the helicopter 90 degrees left towards a downhill path through the trees and lowered the nose hoping to gain more airspeed and rotor RPM. Engine RPM had decreased to approximately 2,450 and continued to decay. The instructor then tried to reach the junction of his driveway and a road but the engine stopped completely and the helicopter crashed into a tree right side first.

The main rotor blades severed the tree trunk several times and struck a smaller tree before the helicopter impacted the ground on its left side. At the time of the accident the helicopter's gross weight was about 22 kg below maximum. The accident site was about 496 ft above sea level. The outside air temperature was 17 degrees Celsius and the weather was fine. The instructor reported that the carburettor air temperature gauge read 15 degrees Celsius during the pre-take-off checks. As this reading was out of the yellow band on the gauge, he did not apply carburettor heat for the take-off.

The estimated relative humidity at the accident site was 50 to 55%. Subsequent concerns were expressed by the company operating the helicopter that carburettor icing may have caused the engine failure. The operator reported experiencing symptoms of carburettor icing and the engine stopping in this helicopter during past practice autorotations with the engine idling. Prior to the accident, the operator had prompted company pilots to be very vigilant of carburettor icing and diligent in the use of carburettor heat, particularly during practice forced landings.

The operator was also concerned at the higher-than-expected fuel usage in their 269C-1, which had the standard non-fuel-injected engine, compared to their 269C helicopters with the standard fuel-injected engine. (The Schweizer 269C-1 is also commonly known as the 300CB, whereas the 269C is commonly known as the 300C.) The operator reported that their 269C-1 used about 48 litres per hour, whereas their 269C helicopters averaged about 41 litres per hour. The operator wondered if the additional fuel used by the C-1 model may have made it more prone to carburettor icing.

The damaged helicopter was retrieved to a hangar and subsequently inspected. An engineer/investigator from Schweizer Aircraft Corporation assisted in the investigation. No fault was found with the airframe or the engine which may have contributed to the accident. No evidence was found to prove that carburettor icing had occurred. Carburettor icing is not normally encountered at or near full engine power unless high humidity or visible moisture is present. The reason the engine failed could not be determined.

The Precision Airmotive Corporation, HA-6 10-6030 carburettor was originally fitted to Schweizer 269C-1 helicopters. On 5 March 1998, the manufacturer issued Service Information Letter - Fuel Systems, SIL MS-3, Revision 1, for the mandatory conversion of carburettors in all Schweizer 269C-1 helicopters to the HA-6 10-6030-1. Helicopters with airframe serial numbers 0001 to 0073 were to be retrofitted, whereas all subsequent factory models will be equipped with the modified carburettor before sale. The conversion involved installing a new secondary nozzle, a new power jet, a new idle tube, adjusting the air metering valve and adding an acceleration pump circuit.

As well as the reconfigured carburettor, the retrofit included an air straightener, removal of one engine baffle, relocation of the cylinder head temperature probe and relocation of the optional exhaust gas temperature probe, if so equipped. The intention of the reconfigured carburettor, combined with the air straightener was to establish improved fuel distribution and better fuel economy.

Soon after some parachutists had exited the aircraft and the pilot had commenced descent the lower section of the left engine cowl came free of the aircraft. The upper section of the cowl remained attached at its trailing edge and wrapped around the wing leading edge outboard of the engine.

Speed at the time of the failure was between 150 and 160 kt. The parachute drop had been conducted from 12,000 ft and the pilot thought that the cowl was lost around 10,500 ft.

The pilot reported that full aileron and almost full rudder deflection were required to maintain control of the aircraft during the descent. A speed of 120 kts, and full power on both engines was required to achieve sufficient control to land the aircraft.

The maintenance organisation responsible for the aircraft had conducted an inspection prior to the flight. One person had experienced difficulty in securing the cowl screws on the outboard side of the propeller spinner and had omitted to secure the inboard side. This error had not been detected by the supervising engineer nor the pilot during subsequent inspections.

The maintenance manual contains a warning about the need to maintain indicator patches on the cowls to indicate the locked position of the cowl fastener screwdriver slot. These indicators were not fitted to the aircraft. The cowl fasteners also include an indicator pin which protrudes into the screw slot when the fastener is locked. The pilot was not aware of this feature at the time of this occurrence.

On the morning of 16 October 1997, Boeing 767 ZK-NBC was prepared at Sydney (Kingsford-Smith) Airport for a flight to New Zealand. When one of the engines was found to be unserviceable, the passengers and their baggage were offloaded and placed on another flight. In anticipation of the aircraft becoming serviceable, two cargo containers were left in the cargo hold, one secured and one unsecured, and the hold doors were left open. When a change occurs to an aircraft's arrival or departure time, a delay checklist is used by operations staff to ensure that all departments are aware of the new time. Due to deficiencies in the delay checklist, a number of departments of the ground handling company were not advised of the new departure time.

So that repairs and engine runs could be performed, the aircraft was towed from the international terminal to the maintenance area. It is likely that the towing crew closed the hold doors at this time. The decision to move the aircraft was made without advising Ramp Control, who are responsible for the loading.

By late afternoon, new parts for the engine had been located, another flight crew was positioning from Auckland and a new departure time of 2300 hours was planned. A load instruction form was prepared by Load Control, covering the two cargo containers already on board and one additional container which was to be loaded. Ramp Control was not advised of the new departure time, assumed that the aircraft would depart the following morning and did not allocate a loading team. The aircraft was towed to the international terminal at about 2100 for refuelling, but the cargo hold doors were not opened. The load sheet officer reported receiving information that led him to believe that the additional cargo container would be loaded at this time. The flight crew arrived at the load control office to sign the load sheet. The load sheet officer assumed that the containers had been loaded in accordance with the load instruction report and signed the load sheet.

After refuelling, the aircraft with the flight crew onboard, returned to the engine run area for the fitment of parts and engine runs. It was declared serviceable at 2230. The flight crew started engines and taxied for takeoff from the maintenance area. At 2249, 11 minutes before the curfew at Sydney Airport commenced, the aircraft took off for its flight to Christchurch with no passengers onboard. After landing, when the cargo hold was opened, it was found that the unsecured container had moved around in flight but had not caused any damage to the aircraft.

Significant factors in this occurrence were:

1. Poor communications between a number of departments at Sydney Airport.

2. The failure of the load sheet officer to ensure that the aircraft had been loaded in accordance with the load instruction form before signing the load sheet.

3. The priorities of the load sheet officer which placed the departure of the aircraft before the curfew, ahead of adherence to the published loading procedures.

The ground handling agent advised that the following safety action has been carried out to prevent recurrence.

1. A review of the procedures for communications between departments at Sydney airport has been carried out.

2. The delay checklist, used by operations staff to advise departments of changes to aircraft times, has been reviewed.

3. New procedures that require the person responsible for loading to sign the load instruction form on completion of loading, have been introduced.

4. Written instructions have been issued to all ramp and load control staff confirming the operator's loading and documentation procedures.

5. Additional monitors have been installed in the load control and ramp control offices to keep staff advised of delays to aircraft arrival and departure times.

The pilot in command reported that the purpose of the flight was for continuation hover and taxi training for the student. The student had previously flown two hover flights. The weather was fine, and the flight had progressed for approximately 30 minutes.

The student's handling ability had improved to point that he was able to a hover over a fixed position on the ground. He was hovering the helicopter approximately 2 ft above the ground, when it began to yaw to the right and sink. The instructor told the student to apply left pedal, however, before the student or instructor could take recovery action, the tail rotor contacted the ground. The helicopter pitched up and fell back on the ground on the left side. After completing the emergency shut down checks, both the instructor and student were able to egress through the broken nose bubble without injury.

The pilot noticed as he flared the aircraft for landing that the landing gear was not extended. During the subsequent go-around scraping noises were heard. The aircraft was climbed to circuit height and the gear selector was recycled.

The subsequent extension of the landing gear was normal and the aircraft landed without further incident. Damage to the aircraft was confined to the inboard section of the right flap.

FACTUAL INFORMATION

A training flight had been planned for a Royal Australian Air Force (RAAF) General Dynamics F111 from Amberley to Amberley, incorporating a flypast of the Southern Cross school at Ballina East. The flypast was to consist of two overflights of the school. A notice to airman (NOTAM) for the low-level jet route of the F111 had been issued by the RAAF. The NOTAM did not indicate that the F111 would be operating in the area of the school. The route of the F111 to Ballina East was from a position 27 NM west-south-west of Ballina airport to over the airport at 1,500 ft above mean sea level and thence to Coolangatta on climb to 5,000 ft. The weather forecast for the flight indicated that there might be low cloud and showers in the Ballina area.

The crew of the F111 encountered low cloud and reduced visibility west of Ballina airport and descended to 1,000 ft above ground level. The crew made two traffic advisory radio broadcasts to notify aircraft in the Casino/Lismore/Ballina mandatory broadcast zone (MBZ) on the very high frequency (VHF) radio in accordance with Aeronautical Information Publication (AIP) procedures. The crew made a further transmission to notify personnel at the school of the F111's estimate over the school. This transmission was also made on the MBZ frequency. The last two advisory transmissions made by the F111 crew on the MBZ frequency were heard by the crew of a Boeing 737 on the ground at Ballina airport.

This crew also saw a Hughes Lightwing ultralight aircraft conducting circuit training on runway 24 at Ballina, although they did not hear the pilot make or acknowledge any radio broadcasts. The pilot of the Lightwing reported that he had made a taxi broadcast prior to conducting the circuit training. The AIP did not require the pilot to make other radio transmissions. Approximately 3 NM west of Ballina airport, the crew of the F111 encountered visual meteorological conditions (VMC) and tracked for the school. As the F111 passed south of Ballina airport abeam the western end of runway 24, the pilot in command saw the Lightwing to the left of his aircraft. The Lightwing was turning left and was at the same altitude.

Reports indicate that the lateral distance between the aircraft was somewhere between 300 m and 1000 m. Subsequently, the F111 crew contacted the pilot of the Lightwing and established that it had been at the same level. Both aircraft crew were unaware of the other aircraft prior to the visual sighting.

ANALYSIS

It was not determined why the other aircraft did not hear the taxi broadcast by the pilot of the Lightwing. Line of sight very high frequency transmissions may have been adversely affected by terrain shielding due to the low altitude of the F111 as it tracked to Ballina. However, the Lightwing pilot was not required to make regular calls on the MBZ frequency while conducting the training. Because they had not heard transmissions from each other, the pilots of the F111 and the Lightwing were not aware of the other aircraft operating in the MBZ.

The Skyfox Gazelle had undergone maintenance to rectify a flooding carburettor. The left side carburettor bowl had been removed and one of the floats found to be low. The carburettor was then removed and both carburettor floats replaced. The carburettor was re-installed, but when the fuel pump was turned on to prime the fuel system, the carburettor again flooded.

The maintenance organisation reported that the needle and seat were then adjusted until the flooding ceased. No evidence of flooding was found when the engine was ground run to full power, without the electric pump operating. Before commencing a subsequent test flight the pilot conducted another satisfactory full power check. However, shortly after take-off at about 200 ft, the engine lost power. The pilot commenced forced landing procedures, but the engine regained full power at about 100 ft. The pilot re-commenced climbing and returned to the airfield. But once again the engine lost power so the pilot force landed the aircraft on the airfield.

The resulting heavy landing bent the landing gear and damaged a wing tip. During a subsequent ground run the engine was able to attain full power. The left side carburettor was again removed and sent to the engine manufacturer's agent for disassembly and inspection. The inspection revealed that although the carburettor float level was slightly incorrect, it was not considered sufficient to cause the engine to lose power. However, the carburettor air duct was found to be holed and both the needle and float mechanisms were excessively worn. Those components were replaced, and the carburettor re-installed. The fuel system was then pressurised using the electric fuel pump.

The left side carburettor was found to be operating correctly, but the right-side carburettor now flooded. The right side carburettor air duct was subsequently found to be holed, and the needle and seat were excessively worn. It is considered that the combination of holed air ducts and worn carburettor needles and seats probably resulted in an excessively rich fuel mixture, with an associated loss of engine power. The maintenance organisation has supplied a report to CASA.