The aircraft was being vectored for an intercept of the runway 35 localiser at Canberra airport. While flying the 160-degree radial, 17 nautical miles from Canberra, on a heading of 310 degrees at 6,000 feet, a false capture of the localiser occurred. The crew identified the false capture, reselected the heading mode and held that mode until positively established on the localiser. The approach and landing was completed without further incident.

The investigation found that the problem was not new and had been known for a number of years, although very few formal reports had been raised. The domestic operators had issued notices to their Boeing 737 crews advising details of the problem. The operators required that any further occurrences were to be reported to air traffic control, followed up by a formal air safety incident report. The Civil Aviation Safety Authority issued a NOTAM containing similar advice and requirements.

In March 1995 the Bureau's data base was modified to specifically record false localiser captures. In the 18-month period to August 1996 the data base captured 17 events that had affected all the major types of high-capacity regular public transport aircraft on the Australian registry. While the majority were reported on approaches to Sydney airport, false captures were also reported at Canberra, Wellington and Christchurch airports.

False capture results in many different indications depending on the type of aircraft, the equipment fitted, and the mode selected on the autopilot or flight director. With certain modes selected an aircraft can deviate from the desired track and follow the false signal.

Research has shown that this phenomena has been recognised overseas and some work has been carried out in an effort to identify the causal factors.

One group believes that the false capture occurs due to significant scalloping, or signal reversals, in the region of the localiser where the signal is normally saturated. Testing of transmitters at Australian airports by the Civil Aviation Safety Authority has shown that the radiated signals meet the International Civil Aviation Organisations requirements for signal propagation.

Another organisation suggested that the capture criterion for some flight management systems and the algorithm for some digital receivers make invalid assumptions about the localiser signal.

Due to the lack of substantive data, the Bureau's Safety Programs group has initiated a research project aimed at identifying the extent of the problem, quantifying its effect and making recommendations as necessary. The results of the project will be published in due course.

The aircraft took-off normally but climbing through about 400 ft it suffered a sudden, complete engine failure. The pilot carried out emergency procedure checks, which included changing from the left fuel tank to the right, but when this failed to immediately restore power he changed back to the left tank and pumped the throttle vigorously without success. The pilot then carried out a forced landing into the sea adjacent to the shore. All occupants evacuated the aircraft uninjured.

The aircraft had been refuelled the previous day to its maximum capacity of 330 litres and then flew for 2.3 hours. The pilot then dipped the fuel tanks which showed 170 litres of fuel remaining. The next morning, he did not recheck the fuel quantity using the dip stick but relied on the fuel gauge readings which at times are inaccurate. These indicated 40 litres in the left tank and 80 litres in the right. The aircraft then flew for another .6 of an hour using the left tank. The engine failed during the next take-off.

An inspection of the aircraft revealed that the right tank contained fuel, but the left tank was empty. The fuel consumption rate was advised as being 70 litres/hour.

The pilot had not selected the tank which indicated the greater quantity of fuel for take-off, and when the engine failed he changed from the left tank to the right, but did not wait long enough for air to expel from the engine fuel feed line to allow resumption of fuel flow from the right tank to the engine. Pumping the throttle would not have had any effect on regaining power as the engine is fuel injected.

The aircraft was being used for a pipeline survey, involving a number of landings and take-offs, prior to the accident. As the aircraft approached Red Hill, a survey check point, the pilot noticed that the fuel gauge indicated that the equivalent of 170 l of fuel remained. He elected to proceed to Paraburdoo, 116 NM away, to refuel. The pilot calculated that the trip would take 77 minutes, and he would arrive at Paraburdoo with approximately 40 l of fuel remaining (the minimum operational requirement).

About 20 minutes after leaving Red Hill the pilot noted that the fuel gauge still indicated 170 l. It remained at this reading for a further 10 minutes before beginning to oscillate and fall rapidly. The pilot reassessed the readings and determined that he still had sufficient fuel for the flight.

Approximately 5 km north-west of Paraburdoo, as the aircraft was descending through 3500 ft, the turbine temperature and engine RPM began to fluctuate. The pilot assumed an engine malfunction and entered an autorotational descent rather than risk a more significant problem during a normal approach.

When 500 ft above the ground the pilot observed that the area he had selected for landing was unsuitable. He adjusted his approach to land at a more suitable site however, it was further away. During the extended glide, to the new site, the pilot allowed the rotor RPM to decrease (the low RPM warning sounded during the approach) and in the ensuring heavy landing a main rotor blade struck and damaged the tail boom. The engine continued to run at idle during the approach and was shut down by the pilot after landing.

A post-accident inspection found that the fuel gauge indicated the fuel tank contained the equivalent of 19 l of fuel.

Draining the tank retrieved around 15 l of a fuel/water mixture (confirmed by laboratory testing) from the aircraft. Additional fuel/water was found when the fuel contents sender units were removed for testing. Tests on the fuel contents sender units indicated that it was possible for the gauge to stick between readings of 114 and 190 l.

Calculations indicate that the helicopter left Port Sampson with an endurance of 220 minutes and that it had been operating for about 206 minutes at the time of the engine malfunction. The low fuel pressure lights did not illuminate during the accident sequence indicating that the fuel inlet remained covered at all times. Background information indicates that the turbine engine fitted to the Bell 206 helicopter is tolerant of water held in suspension in the fuel however, ingestion of a fuel/water mixture where the percentage of water has increased as a result of its settling out of the fuel into the bottom of the tank, may cause fluctuations similar to those reported by the pilot.

The most likely reason for the engine malfunction was that the low fuel state raised the percentage of water in the fuel/water mixture to a point where it began to effect engine performance.

Evidence indicates the pilot did not carry out water disclosing check at Port Sampson prior to departure. Had he done so he may have determined that water was present and taken action to correct the situation before it led to an emergency landing.

The low RPM state prevented the pilot from arresting the descent sufficiently to prevent a heavy landing.

The pilot did not complete a flight plan or a fuel log for or during the flight. Consequently, he had to rely solely on the fuel gauge indications which, in this case, may have been incorrect.

The pilot was conducting a landing in a paddock to retrieve a glider from an out landing. During the landing roll the aircraft skipped slightly for approximately 15 m then pitched forward, the propellor struck the ground and the aircraft came to rest inverted.

The pilot said later that he may have relaxed prematurely after a reasonable satisfactory touchdown. The landing had been into a wind of about 10 kts.

The pilot stated that after successfully completing six circuits and landings with an instructor on board he commenced a period of solo circuits. During the fourth circuit, on final approach for runway 29, he was instructed by air traffic control to go around and make a right hand circuit for runway 36 and cleared for a touch and go landing. A normal approach was carried out, then after touching down at 80 knots the aircraft ballooned slightly. The pilot lowered the nose allowing the aircraft to wheelbarrow on its nosewheel and veer sharply to the left. The pilot applied right rudder to correct the swing, but the aircraft continued to slide sideways into a large drain.

When the Roulettes were cleared into the MCG from Point Ormond (PTO) at the start of the rehearsal, the airspace release that was issued by the departures (DEP) controller to the EN aerodrome controller (ADC) was "PTO to the MCG keep clear of the 26 localiser".  Prior to the start of the rehearsal an onwards clearance for the Roulettes that were to proceed to ES was issued by DEP to EN. The clearance was "track direct to MB maintain 5000 feet” Only the Roulette leader was operating a transponder.

After the Roulettes had started the rehearsal the EN ADC requested departure instructions for VH-SRJ who was departing runway 17 at EN to track via the 150 Melbourne (ML) VOR radial to Cowes (CWS) at 3000 feet. A heading of 170 or 180 was also requested to keep VH-SRJ clear of the Roulettes. DEP issued a heading of 170 unrestricted. VH-SRJ departed and remained on EN TWR frequency. The pilot of VH-SRJ was passed traffic advice on the Roulettes and reported that he had them in sight. When VH-SRJ was transferred to DEP frequency abeam Westgate Bridge (WEG), the pilot said he still had the Roulettes in sight. VH-SRJ was then vectored onto the 150 radial at 10 miles from EN by which time the aircraft was cruising at 3000 feet.

Meanwhile, the Roulettes had advised EN ADC that they had completed their Airwork and wanted an onwards clearance. EN ADC then called DEP for a clearance "MCG to Yarragon (YAR)". DEP then confirmed the previously arranged clearance of "direct MB maintain 5000 feet". EN ADC then asked the Roulettes about their details for departure and the leader advised two for LV and four for ES. EN ADC then cleared the two for LV to depart via Station Pier (SNP) at 2000 feet. The leader of the Roulettes then requested that the formation depart on a southerly heading to facilitate the breakup of the formation. This was approved by the EN ADC who then advised the four Roulettes that were bound for ES that once they were south of PTO or clear of controlled airspace to climb to 5000 feet. The EN ADC continually kept the Roulettes and other traffic holding outside EN airspace informed of each other.

At this stage DEP could see the transponder return of the Roulette leader heading for PTO at 2000 feet at 230 knots groundspeed but could not see any primary returns from the rest of the formation. He then asked EN ADC where the Roulettes were as he was expecting to see some return in the MCG area. EN ADC advised they were in the PTO area. At this time VH-SRJ was just south of and abeam PTO cruising at 3000 feet. The Roulettes that were bound for LV, including the leader using a transponder, then did a left orbit at 2000 feet and proceeded to LV.

A few seconds later a primary return was observed approximately four miles west of the 150 radial making a sweeping left arc towards MB. The formation bound for ES then called DEP and was immediately asked their present level which was reported as "left 3400 feet". A transponder code was then issued to this formation which was identified heading east towards MB leaving 4500 feet two miles east of VH-SRJ. The primary return from this formation passed within one mile ahead of VH-SRJ.

Analysis

EN TWR received a telephone call from the Roulette leader to arrange the area for the practice display. There was no consideration given to callsign requirements after the formation breakup. The display area was not specifically co-ordinated between EN TWR, DEP or the Roulette leader via intercom or air to air communication.

The DEP controller expected the Roulettes that were bound for ES to be departing from the MCG direct to MB which would have kept them clear of the 150 radial and VH-SRJ. However, the original airspace release from DEP to EN was PTO to the MCG up to 4000 feet and clear of the EN 26 localiser. Had there been a more precise description of the airspace release and onwards clearance then the EN ADC may have been more aware of the need to co-ordinate with DEP prior to clearing the Roulettes to track south.

DEP was unaware that the EN ADC had cleared the Roulettes to track south to PTO until he asked. When the Roulettes asked to track south, they were already almost over PTO with an airspeed of close to four miles a minute.

The incident occurred during a peak traffic period when both DEP and EN TWR were handling moderate to heavy traffic levels. Both the DEP controller and the EN ADC were experienced in their respective positions

Significant Factors

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

1. Co-ordination between the Roulettes, DEP, and EN TWR, both before and during the exercise was loose and lacking in specific detail.
2. Callsigns for the Roulettes after the formation breakup had not been addressed prior to the display. This resulted in the DEP controller having to access another transponder code for the ES bound aircraft at a critical period of the flight.
3. The DEP controller never issued a precise description of the airspace that was released to EN ADC.
4. EN ADC likewise did not ensure that the precise lateral and vertical limits of the airspace required by the Roulettes was co-ordinated with DEP. As a result, the Roulettes were not restricted to a specific block of airspace for their display.
5. DEP did not give a precise onwards clearance for the ES bound formation. A clearance should have been issued to ensure the formation set course from the MCG direct to MB. This was critical for separation with VH-SRJ.
6. The EN ADC did not recognise the significance of the need to co-ordinate with DEP the request by the Roulettes to track south to facilitate the formation break.

Safety Action Taken

1. The DEP and EN TWR controllers were taken off their rosters and given appropriate counselling.
2. A standardisation item is to be issued by Air Traffic Services (ATS) in Melbourne to highlight the need for precise descriptions of airspace releases along with a reminder of the need to take performance characteristics into account when formulating airspace releases.
3. Another standardisation item is to be issued to highlight the importance of being specific when defining a route clearance, particularly when it involves separation with another aircraft. This item will include a reminder that it is imperative that co-ordination is effected before any approval is given that may change the conditions of an issued clearance.
4. Discussion is taking place among ATS supervisory staff as to the best way of co-ordinating these types of activities between all involved parties to ensure that correct briefing and co-ordination is achieved.

Sequence of Events

The crew of VH-OGO, when established on final approach to runway 33, reported a TCAS RA (Resolution Advisory) against an unknown aircraft indicating half a nautical mile west at the same level, 1,000 ft AMSL. The other aircraft, VH-HSC, a helicopter, was tracking west of the Cook Highway to the south-eastern training area. A breakdown in separation had occurred.

The pilot of the helicopter had been given a clearance by SMC (Surface Movement Control) to track to the western training area via Green Hill. The ADC (Aerodrome Controller) later amended this clearance for the aircraft to remain west of the Cook and Bruce Highways. The departure of the helicopter was not monitored by the ADC due to distractions in the Control Tower. The ADC expected the helicopter pilot to track directly to the south-western section of the Bruce Highway which is due south of the aerodrome. The pilot instead tracked west of the Cook Highway which closely parallels the final approach path to runway 33.

Analysis

When the two aircraft passed each other, the helicopter which had not reached the junction of the two highways was still being operated within its clearance restriction of "west of the Cook Highway", although this was not what the ADC intended. The ADC failed to monitor the helicopter's departure thus did not ensure adequate separation of the outbound helicopter and the inbound passenger jet.

Safety Action

As a result of this incident, a caution has been inserted in the Air Traffic Services Local Instructions stating that at a departure clearance west of the Cook Highway does not provide separation with final runway 33.

The pilot flared the aircraft for landing too early, in strong gusty wind conditions. Corrective action was not undertaken. As a result, the aircraft landed heavily, collapsing the right main landing gear.

The aircraft made a normal approach and landing on runway 05. As the aircraft was approaching the parking bay tarmac personnel noticed that a section of leading-edge flap was missing from the right wing outboard leading edge. This was later found by the aerodrome safety officer during a runway inspection.

The crew reported that the aircraft had operated normally during the flight.

Investigation revealed that after departure from Melbourne, as the leading-edge flaps retracted, the follow-up mechanism malfunctioned allowing the flap actuator to continue driving the flaps when fully retracted. This caused a flap attachment bracket to fail. When the flaps were selected down the actuator operated normally, with no abnormal indications noticed by the crew. The section of flap associated with the failed bracket separated from the aircraft after landing.

The cause for the follow up mechanism to malfunction could not be determined, and a report from the company has not been forthcoming.

The pilot was conducting joy flights in the vicinity of an active car racetrack. The helicopter type was recently introduced into Australia and is a relatively new design. VH-APM had accrued only 128 hours total time since new.

The pilot took off into a 15-knot wind with three passengers on board. The helicopter was operating at less than maximum gross weight, with a significant power margin. The pilot advised that when the helicopter was about 100 feet above the ground, climbing at about 55 knots, he felt a slight airframe vibration and heard the engine noise increase slightly. The vibration level continued to worsen. The pilot had no idea what was causing the vibration or how serious it was. He elected to land the helicopter as soon as possible. As there was no suitable landing site immediately ahead, he turned back to the departure helipad and instigated a power-on (needles joined) autorotative descent. Nearing the ground the pilot flared the helicopter, which was facing downwind, and applied maximum power, but was unable to eliminate the rate of descent. The helicopter sank through the flare and landed heavily, tail low, short of the helipad, in the clear take-off departure path area, with five to 10 knots groundspeed.

Subsequently engineers discovered that the engine cooling fan had come loose on its shaft thereby causing the vibration. A crack was also discovered on the forward face of the fan wheel.

CONCLUSIONS

Findings

1. The engine cooling fan came loose on its drive shaft.

2. The loose cooling fan caused a vibration through the airframe.

3. The loose fan may have caused the engine to "hunt".

4. The pilot did not know what was causing the worsening vibration.

5. The nearest suitable site for a landing was the departure helipad.

6. In an attempt to land the helicopter as soon as possible, the pilot entered a power on autorotation and terminated with a downwind flare.

7. The helicopter landed heavily with the tail low.

Significant Factors

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

1. The pilot reacted quickly to a sudden, unusual, worsening vibration in flight.

2. Because of the tailwind effect, combined with a rapid descent plus a nose high flare, versus the available power, the pilot was unable to arrest the descent.

SAFETY ACTION

The helicopter manufacturer issued R44 Service Bulletin #2 on 24 October 1994 to all R44 owners, operators and service centres for an inspection to be done on cooling fans within 10 flight hours and thereafter every 25 hours until the fan wheel is replaced with a D174-1 Rev. G or later fan wheel.