British BAE 125-1000A N520QS

Summary

On 11 September 2004 at about 16:38 local time, a British BAE 125-1000A registered N520QS was involved in an accident near San Francisco, California, United States. 2 people were on board and nobody was injured. The aircraft was substantially damaged. The NTSB has published a probable cause for this accident; it is quoted in full below.

Date

11 September 2004 at 16:38

Classification

Accident

Location

San Francisco, California, United States

Nearest airport

San Francisco International (KSFO)

Coordinates

37.6189, -122.3747

Aircraft

British BAE 125-1000A

Registration

N520QS

Category

Airplane

Engines

2

Operator

Not recorded

Operating rule

Part 91: General Aviation

Purpose of flight

Positioning

Phase of flight

Not recorded

Route

San Francisco → North Las Vegas

Aircraft damage

Substantial

Weather

VMC

Light

Day

NTSB number

LAX04LA334

Nobody was injured.

An electrical arc from an undetermined source initiated a hydraulic line rupture, which resulted in an equipment bay fire.

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

Read the full NTSB narrative

The business jet experienced a fire in the aft equipment bay while holding short for takeoff. The two-person aircrew were performing a positioning flight. While the airplane was holding short for takeoff, the crew noticed a Master Caution and a Pack & Aux Overheat warning light illuminated on the cockpit annunciator panel, followed by a Rear Baggage Smoke Detector warning light. The crew shut down the APU. The captain declared an emergency and the crew evacuated the airplane. Fire crews arrived shortly thereafter, and determined that the fire had extinguished itself. Examination of the aft pressure bulkhead by the manufacturer revealed metal discoloration and soot residue, and it was determined that there was structural damage to the aft pressure bulkhead due to a heat induced loss of material temper. After the incident the operator inspected the aft equipment bay and identified a hydraulic line with a pinhole leak. The stainless steel hydraulic line had a small crater like deformation with evidence of recast metal and a 0.005-inch hole at the base of the crater, which is consistent with damage caused by an electrical arc. There was no evidence of chafing on the hydraulic line. Copper, cadmium, and nickel material were acid rinsed from the crater; none of which are listed as alloying element in stainless steel. Copper wire is commonly used as an electrical circuit conductor. A pinhole leak could be expected to atomize the hydraulic fluid that was at 3,000 psi. The hydraulic system working fluid used was Aeroshell Fluid 41, which has a reported flash point between 221F and 230F. The electrical looms/cables that were in the aft equipment bay were disposed of prior to the Safety Board initiating the accident investigation; therefore, determination or identification of the electrical arc source was not possible.

Quoted verbatim from the NTSB record.