On August 12, 2004, at 1812 eastern daylight time, a Mooney M20K, N231LK, was substantially damaged while landing at the Vineyard Haven Airport (MVY), Edgartown, Massachusetts. The certificated private pilot and passenger received minor injuries. Visual meteorological conditions prevailed, and an instrument flight rules flight plan was filed for the flight which departed the North Philadelphia Airport (PNE), Philadelphia, Pennsylvania, about 1600. The personal flight was conducted under 14 CFR Part 91. According to the pilot, the flight from PNE was conducted at 9,000 feet, and uneventful. Upon arriving in the MVY area, the pilot was informed to expect a visual approach to runway 24. While on the downwind leg for runway 24, the tower controller asked the pilot if he could make a visual approach to runway 15. The pilot replied that he could accept the visual approach to runway 15, and made a left hand turn towards the runway. During the final approach to runway 15, the pilot recalled that his approach speed was approximately 90 knots, and he was slowing the airplane for landing. Suddenly, and without warning, the left wing dropped, and the pilot was unable to control the airplane with aileron inputs. The airplane descended, and impacted the ground about 900 feet prior to the runway threshold. The pilot added that the engine was producing power at all times and when the left wing dropped he applied full power. The pilot subsequently stated on his submission of NTSB Form 6120.1/2 that while in the pattern for runway 24, the controller asked him if he could use runway 15. The pilot agreed, and made a right 90-degree turn toward runway 15. During the turn, the pilot reduced the speed to 90 knots, and performed s-turns to lower his altitude. Approximately 15 seconds before landing, the airplane encountered a wind shear, "one wing went down, one wing went up," and the ailerons did not seem to respond to inputs. One wing then struck a tree, and the airplane landed in bushes prior to the runway. The pilot also recalled that the airspeed indicator did not show a reduction of airspeed any less than 90 knots, and no stall warning sounds were heard during the approach to the runway. The pilot subsequently stated on the NTSB Form 612.1/2, under the heading of Mechanical Malfunction Failure section, "Airspeed indicator malfunctioned and showed a higher airspeed than actual airspeed," and under the heading of "Owner/Operator Safety recommendation, "Pilot should not be permitted to change runway assignments after instructions and approach has been initiated for another runway." The airspeed indicator from the cockpit was removed from the wreckage and forwarded to the Safety Board. The indicator was then tested using a certified pitot-static field test unit. The indicator was tested from a range of 60 knots to 180 knots, with a maximum variance of +/- 2 knots observed. No leaks of the indicator housing or tubing attach points were observed. According to the air traffic controller at MVY, the winds were fluctuating, with gusts to 20 knots. She had no reports of wind shear prior to the accident. A wind-shear report of +/- 5 knots was reported approximately 1-hour after the accident. The winds reported at MVY, about the time of the accident, were from 150 at 14 knots.