Bulmer LANCAIR IV-P N5473

Summary

On 10 May 2006 at about 19:25 local time, a Bulmer LANCAIR IV-P registered N5473 was involved in an accident near Somerset, Pennsylvania, United States. 2 people were on board and 2 died. The aircraft was destroyed. The NTSB has published a probable cause for this accident; it is quoted in full below.

Date

10 May 2006 at 19:25

Classification

Accident

Location

Somerset, Pennsylvania, United States

Nearest airport

Somerset County Airport (2G9)

Coordinates

40.0389, -79.0144

Aircraft

Bulmer LANCAIR IV-P

Registration

N5473

Category

Airplane

Engines

1

Operator

Not recorded

Operating rule

Part 91: General Aviation

Purpose of flight

Positioning

Phase of flight

Not recorded

Route

Somerset → Unknown

Aircraft damage

Destroyed

Weather

VMC

Light

Day

NTSB number

NYC06LA112

2 people died.

The pilot's failure to maintain sufficient airspeed after takeoff to preclude a stall, which resulted in a loss of control and an inadvertent stall. Factors associated with the accident are the inadvertent stall, the loss of engine power due to the pilot's inadvertent activation of the high pressure auxiliary fuel pump, and the pilot's failure to abort the takeoff after receiving abnormal engine and fuel flow warnings on the primary flight display.

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

Read the full NTSB narrative

The experimental airplane had accrued 27 hours of total flight time, and had just completed its 25-hour Phase I flight testing period. Witnesses related that they saw the airplane engine start, and that the crew appeared to go through an extensive series of checks for approximately 10 minutes prior to takeoff. The engine idled smoothly, and was accelerated several times prior to taxi, once to full power. At takeoff, with a tailwind, the airplane accelerated smoothly, and rotated at a point along the runway that the witnesses thought was later than usual. The airplane pitched nose-up about 20 to 30 degrees in the climb, and the landing gear retracted. When the airplane reached treetop height, black smoke trailed from the engine exhaust system, and the engine "sputtered." The airplane entered a smooth roll to the left, yawed left, and then "plunged" to the ground, in a near vertical attitude. Witnesses said the turn after the loss of engine power was performed at a very high deck angle. Examination of data extracted from the airplane's electronic flight instrumentation system revealed that during the takeoff roll, the fuel flow was more than 20 percent above maximum, and the propeller was over-speeding. The engine rpm, fuel flow, and "Engine" warnings on the multi-function displays should have been visible to the crew. Examination of flight data revealed that the airplane continued to pitch-up as high as 22 degrees, as altitude decreased and airspeed decayed. Examination of the cockpit schematic revealed that the auxiliary fuel pump "high boost/low boost" switch was positioned next to the "Nav" lighting switch. In the airplane's "Before Takeoff" checklist, the "Lights-as required" task was to be performed four tasks prior to the "Takeoff" checklist.

Quoted verbatim from the NTSB record.