NTSB Factual Report

On May 21, 2001, approximately 0955 eastern daylight time, a Beech 55, N4783M, was substantially damaged when it impacted vehicles after an aborted takeoff at the Brandywine Airport (N99), West Chester, Pennsylvania. The certificated private pilot was not injured. Instrument meteorological conditions prevailed and an instrument flight rules flight plan was filed for the personal flight conducted under 14 CFR Part 91.

In a written statement the pilot stated:

"I was the only occupant. Departing N99 for an IFR flight to Reading, ultimate destination Colorado. Had full fuel. Pre-flight inspection was normal, no discrepancies. Pre-flight run-up was normal, no discrepancies. Taxi to runway 9 was normal. Received clearance and release from Philadelphia clearance for flight to RDG. Taxied onto runway 9. Ran engines up (with brakes). RPM and M.P. were normal and equal. Initial acceleration was normal. RPM and M.P. showed full power. Checked airspeed for redline (+5). Was at 65k. Scanned r.w., checked airspeed again. Still at 65k. Airspeed needle never hit redline (79kt). Aborted takeoff. Aircraft skidded and ran off end of runway. It was raining. Runway was wet. When I cut power and applied brakes, aircraft hydroplaned, skidded, and ran off the runway."

A Federal Aviation Administration (FAA) inspector performed an on-scene examination. According to the inspector, the airplane impacted several cars and came to rest in a parking lot off the end of the runway 9, a 3,347-foot runway. The inspector reported there were no skid marks on the runway, and that the airplane sustained substantial damage. The right wing and all three landing gear wheels were separated from the airplane, and the fuselage was "split open." Additionally, the airspeed indicator read 0 knots.

According to the FAA inspector, an airspeed calibration test was performed on the airplane and the airspeed indicator read about 10 knots higher than the test equipment. Further examination of the system revealed that the pitot tube was blocked with a "corrosion-type material". The airspeed indicator was then removed from the airplane and bench tested. The indicator read about 4-5 knots higher than the test equipment.

Examination of the airplane logbooks revealed that the most recent pitot-static system check was performed on March 14, 2001.

The pilot reported 864 hours of total flight experience, 40 of which were in make and model.

Weather at Philadelphia International Airport, about 16 miles to the southeast, at 0954, was reported as winds from 070 degrees at 8 knots, visibility 7 statute miles, overcast ceiling at 900 feet, temperature 14 degrees Celsius, dew point 13 degrees Celsius, and altimeter setting 30.08. According to surface observations recorded at the airport, rain had been falling since 2236, on May 20, 2000.

NTSB Probable Cause

The partial blockage of the pitot/static system, which led to an inaccurate airspeed indication, and resulted in an aborted takeoff and runway overrun. A factor was the wet runway.