AAIB Bulletin #: 12/96 Ref: EW/C96/9/1 Category: 1.3

Aircraft Type & Registration: WAR Hawker Sea Fury Replica, G-BLTG

NO & Type of Engines: 1 Rolls Royce 0-200-A piston engine

Year of Manufacture: 1986

Date & Time (UTC): 1 September, 1996 at 1445 hrs

Location: Crosland Moor Airfield, Huddersfield

Type of flight: Private

Persons on board: Crew - 1 Passengers - none

Nature of Damage: Aircraft Destroyed

Commander's Licence: Private Pilot's Licence

Commander's Age: 69 years

Commander's Flying Experience: 2,528 hours (of which 6 were on type)

Last 90 days - 4 hours

Last 28 days - 2 hours

Information source: AAIB Field Investigation

History of flight

The pilot gained his PPL in 1965. Most of his flying in recent years had been in a Jodel D11, about 30 hours per annum. In May 1996, he purchased the Sea Fury Replica and based it at Leeds-Bradford Airport. On 26 August, the pilot flew the aircraft from Leeds-Bradford to Elvington Airfield. While at Elvington, the iarcraft uplifted 24 litres of Avgas. The return flight to Leeds-Bradford took some 15 minutes. The aircraft next flew on the day of the accident, departing from Leeds-Bradford at 1220 hrs and arriving at Crosland Moor Airfield around 1300 hrs. The aircraft carried out a low pass followed by a circuit and landing on arrival. A fly-in social event had been organised at the airfield that day.

Prior to departure, the aircraft was held in a queue for several minutes, while waiting to backtrack for a departure from Runway 25. No abnormalities were noted by any of the spectators during this period. In sequence, the aircraft backtracked the runway and commenced its take-off run. Eyewitnesses observed that after lift off, the aircraft accelerated and the landing gear was retracted while still at low level. On passing the western boundary of the airfield, the aircraft was observed to pull up into what was described as a steep climbing attitude, during which the aircraft's speed began to decay. The aircraft then entered a steep banked turn to the left, with some eyewitnesses estimating the bank angle to approaching 90*. The aircraft then appeared to sideslip to the left and then yawed and rolled to the left, assuming a steep nose down attitude. The aircraft continued to yaw and roll to the left and the flight path angle was initially steep, but was reducing by the time the aircraft impacted the ground, left wing low, in a farm field adjacent to the airfield. There was no fire, but the pilot sustained fatal impact injuries, and a post-mortem examination did not reveal any condition which may have led to pilot incapacitation.

The surface wind was estimated as being from about 30* right of the runway direction, generally light but with occasional increases. An aftercast from the Meteorological Office indicated that at the time of the accident there was a westerly airstream established over the area with weak frontal systems moving east across Scotland. The visibility was 30km and there was no significant weather. The cloud was scatteredwith a base of 3,000 to 4,000 feet, with a higher level broken cloud layer around 8,000 feet. The surface wind was estimated to have been 270*/5 to 10kt and the temperature +19*C. The wind at 2,000 feet was 280*/15kt. Given the local topography of rolling hills, some funnelling effect was possible, but in the opinion of the Meteorological Office, the wind speed was unlikely to have been greater than 15kt.

During the course of the steep left turn, the aircraft turned through the downwind track. Investigation of previous flights made in this aircraft by this pilot could not find any previous occasion when he had performed such a manoeuvre immediately after take-off. He had written to the Popular Flying Association (PFA) shortly after purchasing the aircraft to enquire as to what modifications or testing would be required to make the aircraft aerobatic. The current PFA Permit Limitations prohibited aerobatics and spinning. The PFA response indicated that the aircraft had an unusually low stick force per 'g' which was considered to make it too easy to overstress the aircraft. The normal requirement is for a minimum of 15lbs pull force at the design maximum positive 'g' limit of _6'g' with the cg at the aft aerobatic limit. A weight and balance check indicated that the aircraft was operating within the maximum permitted weight and normal centre of gravity range at the time of the accident.

AIRCRAFT DESCRIPTION:

The WAR SEA FURY was designed by the War Aircraft Replica company of Santa Paula, California, in the early 1970's as a 'kit' or 'plans' homebuilt aircraft. This diminutive half scale aircraft of 20.5 feet wing span was powered by a 100HP Rolls Royce Continental piston engine driving a fixed pitch propeller, and was constructed in the UK, from plans, between 1981 and 1985, since when had flown for approximately 100 hours. The basic structure of the aircraft is wood, with the scale aerodynamic profiles being achieved by shaped rigid foam panels skinned with GRP sheet. The retractable main landing gear on this example was hydraulically operated by a handpump in the cockpit, this reportedly requiring some 20 pumps for full gear retraction.

IMPACT PARAMETERS:

The aircraft had crashed into a grass covered field, some 250 meters to the south of the start of Runway 07, whilst on a track of 060*M, narrowly avoiding a dry stone wall. Analysis of the ground marks and wreckage distribution showed the aircraft to have been erect at the time, but in a left wing and nose low attitude. Its vertical speed was assessed as being relatively high but with low horizontal velocity, the wreckage trail being only some 75 feet in length. This was compatible with the aircraft being in stalled condition, and moving downwind, at impact. There was evidence from the damage to the propeller that it had been rotating under power at the time the first blade struck the ground, and from the areas of contaminated grass along the trail, that the tank contained a reasonable quantity of fuel. The aircraft's configuration at the time was determined to have been with the landing gear and airbrakes/flaps retracted and the canopy closed.

WRECKAGE EXAMINATION:

The wreckage was examined both in-situ and afte recovery to the AAIB at Farnborough. It was established that the aircraft had been complete and structurally intact, all failures being attributable to impact with the ground. This had shattered the left wing and cockpit structure, but the right wing, engine/cowling and fuselage aft of the cockpit, although all damaged, had survived relatively intact. It was determined that all flying control linkages and engine controls had been connected prior to the impact, and the pitch trim lever was found set at its mid position. A partial strip of the engine and carburator failed to reveal any evidence of pre-accident mechanical failures or defects, and it was established that all fuel lines and filters were free of obstruction and that the magnetos, ignition harnesses and spark plugs have been serviceable. The throttle control was found set at maximum, the mixture control at full rich, the carburator heat control at cold, the fuel tap was found in the open position. The engine speed indicator was found with the needle indicating 2500rpm, this all being consistant with a normal full power take off, but little other useful information was gained from the instruments. The cockpit of this aircraft was small, and fitted with a four point harness. This was found undone but rescue personnel reportedly found it unneccessary to release the straps to recover the pilot. Examination of the harness revealed that it was serviceable with no signs of distress on anhy of the components, and there were no indications on the release mechanism of any witness marks to indicate that it might have self released during the impact.

DOCUMENTATION:

The aircraft had been issued with a Permit to Fly (PTF) by the Civil Aviation Authority in June 1993, and was subject to their specified conditions and operating limitations imposed by the PFA. The PTF remained valid until revoked, but was conditional upon a current Certificate of Validity, issued annually following an inspection and flight testing, by the PFA. G-BLTG possessed such a certificate, which was issued on 26 June 1996.