Ultralight aircraft accidents, experimental aircraft accidents, light sport aircraft accident reports 13

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The Transportation Safety Board of Canada (TSB) investigated this occurrence for the purpose of advancing transportation safety. It is not the function of the Board to assign fault or determine civil or criminal liability.

Other Factual Information

The pilot was qualified for the flight. He had acquired his aircraft in October 1994, and he subsequently took his training on his own aircraft. He obtained his ultralight pilot license in March 1995 and had accumulated 141 flying hours at the time of the accident. The pilot had always flown on his own aircraft.

At the time of the accident, the sky was clear and there was no wind. Several boats were in the channel.

The autopsy revealed that death was caused by multiple trauma sustained on impact when deceleration forces exceeded the limits of human tolerance. The results of toxicology tests conducted at the Civil Aviation Medical Unit (CAMU) of Health Canada located in Toronto, Ontario, were negative.

The Pelican is an advanced ultralight. The aircraft was built in 1988 by its first owner. The aircraft was flown for three years, then was parked at an airport until it was sold to its current owner.

The owner replaced the Rotax engine with a Subaru engine. He also removed the right-hand dual control and installed floats and a new carbon fibre propeller. The pilot later repaired the propeller. The leading edge of one of the blades had been damaged when the propeller came in contact with the engine cowling during a static power test sometime before the accident. The precise nature of the repairs could not be established.

The day before the accident, the owner mentioned that he was not satisfied with the repairs. On the flight made following the repairs, the engine had started to vibrate and the vibrations had damaged the engine mounts. That evening, he repaired the propeller again and also repaired the engine mount. He mentioned at the time that he had doubts about the quality of the repair.

The aircraft struck the ground at almost 90 degrees and flipped over. At the conclusion of the impact sequence, the aircraft fuselage lay flat on the ground, and the wings were upside down on the side opposite to their normal position on the fuselage. Both floats were on the same side of the aircraft. The aircraft was approximately 80 per cent destroyed by the fire.

When the wreckage was examined, only two of the three propeller blades had been found. In an information circular to owners, the propeller manufacturer indicated that the type of propeller used by the owner can be repaired by the user following a certain procedure. However, the manufacturer stated that only propellers with nickel-armored leading edges should be used in floatplane operations. That type of propeller cannot be repaired by the user and must be returned to the manufacturer.

Witnesses stated that, during the flight, the engine seemed to be operating normally. Some witnesses heard variations in the sound of the engine after the vibrations started. They associated the sound with variations in engine power.

A fire broke out a few seconds after ground impact. The tanks in both wings contained fuel. When the owner had installed the engine, he had relocated the battery towards the aft fuselage area for balance. The battery cables ran along the bottom of the fuselage to the front. Evidence of a short circuit was observed on one of the battery cables in the forward cabin area.

The flight controls were examined for continuity. The elevator cables and rudder cables were intact. The aileron control had broken in the tube running between the left and right controls. The aileron bell cranks and the control tubes running from the cabin to each of the ailerons had melted in the intense heat of the fire.

The aileron control was forwarded to the TSB Engineering Branch Laboratory. A rupture test was performed on the end opposite to the one found ruptured in the wreckage examination. The end ruptured at 950 pounds. This evaluation determined that the control had been manufactured in accordance with established safety standards and complied with the manufacturer's standards.

Analysis

The pilot was qualified for the flight, and meteorological conditions were favorable for the flight.

The pilot had made repairs to one propeller blade. However, the precise nature of the repair could not be determined because that blade was never found. However, the pilot did not seem satisfied with the repair, as a previous repair to the same propeller had not produced the desired results.

When the aircraft started to vibrate in flight, all indications are that the pilot tried to come back to the channel and land the ultralight. To that end, he adjusted engine power several times to reduce the vibrations caused by the loss of the propeller blade.

As there were several boats on the water, the pilot executed a 180-degree turn to avoid them before setting the ultralight down. The evidence indicates that the aircraft stalled during this low- altitude turn before crashing on the island and catching fire.

The following Engineering Branch report was completed:

LP 141/95 - Aileron Pushrod Examination.

Findings

1. The pilot was qualified for the flight.

2. The pilot repaired one blade of the propeller and seemed unsatisfied with the results.

3. The pilot was authorized to repair the propeller.

4. One propeller blade separated in flight and was not found.

5. The cause of the loss of the propeller blade in flight could not be determined.

6. The wings of the aircraft started to vibrate shortly before the accident.

7. The aircraft stalled in a low-altitude turn and crashed.

Causes and Contributing Factors

The aircraft stalled in a low-altitude turn after one blade separated from the propeller. The repair to the propeller of the ultralight contributed to the accident.

Editors Note:

While the failure of this propeller may have been the result of improper repair, we have 29 reports of failure of the Warp Drive propeller. In a recent issue of Sport Aviation they list another reported failure of, and also report that Warp Drive does not recommend the use of their propeller on Volkswagen powered aircraft.

AAIB Bulletin No: 8/98 Ref: EW/G98/06/09 Category: 1.3

 AAIB Bulletin No: 8/98 Ref: EW/G98/06/09 Category: 1.3

Approximately 15 minutes after taking off from Cambridge airport for a local flight, the occupants of the aircraft became aware of a strong smell of fuel. An immediate turn-back to the airfield was made, the passenger door was unlatched to aid ventilation and all electrical selections were avoided. When the aircraft arrived overhead the airfield, the fuel cock was turned off and a glide approach was made to grass Runway 23.
Following an uneventful landing, the aircraft was allowed to run onto the southern taxiway in order to clear the runway. As the occupants vacated the aircraft, the pilot noted a flash in the passenger footwell together with a flame travelling along the doped fabric of the right hand side of the fuselage. The aircraft quickly became engulfed by fire and had been damaged beyond repair by the time the Airfield Fire Service arrived.

 The pilot's assessment of the event was that a fuel leak had occurred in the supply lines between the tanks in the wings and the fuel cock, leading to an accumulation of fuel on the floor of the cockpit. When forward motion had ceased, the fuel was able to drip onto the exhaust pipe beneath the passenger footwell, and be ignited by the hot carbon deposits commonly found on two-stroke systems. Unfortunately, the damage to the aircraft was too severe to identify the origin of the fuel leak. The pilot did however recollect that he had experienced a transient resistance to rudder pedal movement whilst taxiing the aircraft, and considered the possibility that a rudder pedal had fouled a fuel line which may have become unclipped from an adjacent part of the tubular steel fuselage framework.

This incident was similar to another which occurred, in January 1998, to an Avid Aerobat, G-BUDH, and which was reported in AAIB Bulletin 7/98. That aircraft also suffered a fire following a strong smell of fuel in the cockpit, and a loose 'T-piece' connector in the fuel line was suspected.

AAIB Bulletin No: 8/98 Ref: EW/G98/06/03 Category: 1.3

The aircraft had taken off on a flight from RAF St Athan to Oaksey Park, near RAF Benson, and was under the control of Cardiff ATC. After routing over Cardiff city at 1500 feet amsl and when mid-way between Cardiff and Newport, the engine began to run roughly. The pilot transmitted a 'Pan' call on the Cardiff RT frequency, requesting a diversion to the nearest airfield. Despite the aircraft's radio transmission being 'almost unreadable' by Cardiff ATC, the pilot was advised that Cardiff Airport was in fact the nearest airfield and given navigational assistance to avoid overflying the city. As a forced landing appeared likely, the pilot elected to remain to the North of the M4 motorway until abeam the Airport, and advised ATC accordingly. A light aircraft flying in the vicinity was requested by Cardiff ATC to follow 'IX'. The latter aircraft steadily lost height until at approximately 500 feet agl the pilot looked for a suitable field in which he could land into wind. However, at about 200 feet agl the engine failed completely and he carried out a forced landing in a field which had a down-slope. The pilot was unable to stop the aircraft before it collided with a fence, but at low speed. He was uninjured and there was no fire. The pilot of the other aircraft passed the position of the forced landing to Cardiff ATC. A South Wales Police helicopter (UKP 32) then flew to the landing site where it was ascertained that the pilot was unhurt; the crew therefore cancelled the call-out of the Emergency Services.

The aircraft was recovered to the UK Rans agent, with the intention of investigation and repair. However, initial examination has revealed no obvious mechanical failure associated with the engine. Further examination of the ignition and fuel systems will take place during the aircraft's re-build. If any significant defect(s) become apparent at that time, they will be reported upon in a future edition of the AAIB Bulletin.

AAIB Bulletin No: 8/98 Ref: EW/G98/05/06 Category: 1.4

The pilot had flown his aircraft from his home airfield at Hoghton, near Preston, to Kemble with an en-route stop at Shobdon for fuel. He reached Shobdon after 1 hour 40 minutes and refuelled with 25 litres, which was consistent with his expected fuel consumption of 14 to 15 litres/hour. Whilst performing his pre-flight engine checks, before taking off from Shobdon, the pilot noticed a slight hesitancy and roughness as the engine was accelerated. Consequently, he prolonged his engine checks but was unable to reproduce the rough running. He then flew uneventfully to Kemble, taking 1 hour, and before returning home later in the day, via Shobdon again, he refuelled with 15 litres; this also being consistent with his expected fuel consumption.

The return flight from Kemble to Shobdon, by an indirect scenic route, was into a freshening northerly wind and took 1 hour 35 minutes. At Shobdon, he refuelled the aircraft with 27 litres. This was slightly more than he had expected, but he was uncertain whether he had refuelled to a full tank at Kemble. The pilot estimated, from his flight time to a point on this first leg of the return flight, that the headwind had been about 10 to 15 mph. He therefore anticipated this wind for the onward flight from Shobdon to Hoghton.

During the pre-flight engine checks at Shobdon, he had a recurrence of the hesitancy and roughness which was more persistent than previously. As a result, he performed extended engine ground running, during which he replaced the spark plugs and cleaned the air filter on the forward carburettor which was wet with fuel. After further ground running of the engine, which then appeared to be operating normally, he took off for Hoghton. The pilot estimated that the total ground running time at Shobdon, after refuelling, had been about 22 minutes.

However after take off the pilot observed, from his handheld Global Position System (GPS) unit, that the wind had increased considerably, beyond that forecast or his estimate based on the previous leg, and his ground speed at one point reduced to 30 mph. A re-estimation of the leg time was made (about 2 hours 10 minutes flight time) which the pilot calculated would give him a half hour fuel reserve at his destination, after allowing for the extra fuel used during the ground running. (The aircraft fuel tank capacity was 45 litres).

Two hours and 16 minutes after leaving Shobdon, when the aircraft was over the north west corner of Chorley with the fuel gauge indicating 1/8 contents remaining and an estimated 6 minutes from his destination, the engine suddenly stopped. The pilot selected a landing field just north of Chorley hospital, but as he manoeuvred for the approach he realised that he would land short since he had not allowed sufficiently for the wind. The pilot therefore sideslipped the aircraft to increase his rate of descent and landed firmly on a small grass area in the hospital grounds. The landing was sufficiently hard to break the right landing gear, but the pilot was able to release himself, uninjured, from the aircraft.

Subsequent inspection of the aircraft by the pilot revealed that there was no fuel in either carburettor and an insignificant amount in the tank. There was evidence some oily fuel staining on the rear fuselage behind the engine.

AAIB Bulletin No: 7/98 Ref: EW/G98/01/03 Category: 1.3

 The Avid Aerobat aircraft is a high-winged monoplane with a tailwheel landing gear. The pilot was taking off on grass Runway 27 following an earlier uneventful flight in the morning. Before take off he refuelled the aircraft with 4 Star petrol, conducted normal pre-flight checks and taxied the length of the runway in order to assess its condition. The grass was described as long and wet; the latter part of Runway 27 sloped downwards and terminated in a deep quarry.

The take off was normal but immediately after lift-off the pilot noticed a smell of petrol and decided to land straight ahead. After landing back he realised that the retardation was too low to stop the aircraft before the end of the runway and therefore applied the brakes fully which caused the aircraft to nose over and come to rest vertically nose down. The pilot was wearing a crash helmet, in accordance with his normal practice, which received some damage, but he was uninjured and managed to exit the aircraft rapidly, after turning off the engine ignition and electrical master switches. He took the aircraft fire extinguisher with him, a dry powder type. A fire started very shortly thereafter and rapidly spread to the cockpit and the remainder of the fuselage. The pilot pulled the safety ring on the extinguisher but was unable to depress the trigger and could not obtain any extinguishant to tackle the fire, which burnt out the fuselage and most of the wings.

The pilot believed that a fuel leak from a tee-piece connector associated with the fuel primer had occurred. He reported that this had previously worn and leaked, when the aircraft had accumulated 70 operating hours since new, and had been replaced. The aircraft had subsequently flown a further 26 hours until the accident. The connector was apparently destroyed in the fire. The Popular Flying Association (PFA) had not received other reports of problems with this type of connector, which is widely used in Rotax engine installations.

The reason for failure of the fire extinguisher was not established and it was disposed of, however, the pilot did note that it was about five years old and the accident occurred within one month of its 'use by date'.

NTSB Report Brief

Accident Narrative:

Occurrence# 1 LOSS OF ENGINE POWER(TOTAL) - MECH FAILURE/MALF Phase of Operation: MANEUVERING Findings: 1. - ENGINE ASSEMBLY,PISTON - SEIZED

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