Hawker Siddeley HUNTER T MK 7 N576NL

Summary

On 17 November 1999 at about 23:49 local time, a Hawker Siddeley HUNTER T MK 7 registered N576NL, operated by Advanced Training Systems INT., was involved in an accident near Mesa, Arizona, United States. 2 people were on board and one was seriously injured, one had minor injuries. The aircraft was substantially damaged. The NTSB has published a probable cause for this accident; it is quoted in full below.

Date

17 November 1999 at 23:49

Classification

Accident

Location

Mesa, Arizona, United States

Nearest airport

Williams Gateway Airport (IWA)

Coordinates

33.3299, -111.6306

Aircraft

Hawker Siddeley HUNTER T MK 7

Registration

N576NL

Category

Airplane

Engines

1

Operator

Advanced Training Systems INT.

Operating rule

Part 91: General Aviation

Purpose of flight

Business

Phase of flight

Not recorded

Route

Unknown → Nas Point Mugu

Aircraft damage

Substantial

Weather

VMC

Light

Day

NTSB number

LAX00LA034

1 person was seriously injured.

The fatigue failure and separation the stage 3 compressor blades due to corrosion pitting of the blade retention lug bores. A factor in the accident was the failure of the various post military surplus operators of this engine to incorporate the manufacturer's recommended modifications to prevent such failures.

Quoted verbatim from the NTSB record. This site does not paraphrase or interpret it.

Read the full NTSB narrative

Following a loss of engine power on the ex-British military jet fighter just after liftoff, the pilot aborted the takeoff on the runway but could not stop prior to over-running the departure end and colliding with a fence and a berm. The pilot and crew chief said that about 5-10 seconds after takeoff a significant compressor stall happened with a loud explosion, followed by engine spool down. The airplane is a two-seat ex-military jet fighter produced in the 1950's and early 1960's by Hawker for service in the British Royal Air Force. Following the airplane's surplus from the RAF, it was imported into the United States and was being flown under a FAA special airworthiness certificate in the experimental category for the purpose of exhibition and racing. According to records at Rolls-Royce, the engine was manufactured in 1954 and sent to the RAF as part of a spares contract. The engine was last in the factory overhaul facility on March 26, 1981, for overhaul at 251 hours TSO. The engine is life limited to 450 hours between overhauls. The last manufacturer's records on this engine documented its installation in another Hawker Hunter by the RAF in 1983, with 392 hours TSO. The operator's engine maintenance records began on June 27, 1990, and documented its installation in the accident airframe at a maintenance facility in Wisconsin. An unsigned handwritten note preceded this entry and stated that the engine had a total run time since overhaul of 436 hours, with 265 hours remaining to overhaul. No documentation was available to support the engine history between leaving RAF service and the installation in the accident airframe. The last entry in the records was dated July 2, 1999, and consisted of an annual inspection at a time of 548 hours since last overhaul. A partial engine disassembly revealed that three third stage compressor blades had fractured from their root fixing lugs and separated. All compressor blades from stages 5 through 10 had fractured through their airfoil sections just outboard of the root. The root lugs from the failed third stage were removed and submitted for metallurgical analysis. All three blades failed due to high cycle fatigue failures, which initiated in the bores of the lug fixing pins. Energy Dispersive X-ray revealed corrosion cracks and pits at the crack initiation site. This engine has a history of high cycle fatigue failures of stage 3 compressor blades due to corrosion pits. Two modifications were introduced by the manufacturer, which incorporated a strengthened lug and a silicon rubber sealant to the bore interface to prevent the corrosion induced fatigue failures. The modifications were performed by the RAF between 1983 and 1986 to in-service and spares stock engines. This engine did not have these modifications incorporated.

Quoted verbatim from the NTSB record.