NTSB Factual Report

On April 15, 2015, about 1530 eastern daylight time, a Piper PA-28-140, N7598R, experienced a total loss of engine power during takeoff from Buffalo-Lancaster Regional Airport, Lancaster, New York. The private pilot, the sole occupant was not injured during the forced landing on airport property, and the airplane was substantially damaged. The airplane was registered to and operated by a private individual under the provisions of 14 Code of Federal Regulations (CFR) Part 91 as a personal flight. Visual meteorological conditions prevailed at the time and no flight plan was filed for the local flight. The flight was originating at the time of the occurrence.

The pilot stated that she did an "extremely thorough preflight inspection of the airplane" while in the hangar because the airplane had not been flown since January 2015. She checked the fuel, oil, and then pulled the aircraft from the hangar. She indicated the total fuel on board was 39 gallons, of which 20 gallons were in the left tank and 19 gallons were in the right tank; she believed the fuel selector was on the left tank position.

After engine start she performed an engine run-up and reported, "everything was fine." She indicated the rpm dropped 50 during a check of each magneto. She checked the automated terminal information service (ATIS) and noted the wind favored runway 08. She taxied to runway 08, and did the pre-takeoff checklist items. She taxied onto the runway, applied full power and reported the tachometer indicated full red-line rpm. She rotated at 60 miles-per-hour, and when at the end of the runway at an estimated altitude of 200 feet, the engine "coughed" and the airplane began losing altitude. The engine power was restored, and she thought about turning to land on runway 26, but the engine quit again. She knew she had to land straight ahead, and touched down first on the main landing gear in an abandoned field with high grass. The nose landing gear hit rising terrain causing it to collapse. The airplane came to rest in a nose-low/tail-high attitude, and after coming to rest she could hear the electric fuel pump operating. She secured the airplane, and found her cell found and called the mechanic/airport manager to notify him of the accident.

Following recovery of the airplane, the Lycoming O-320-D3G engine, S/N L-11402-39A, was inspected by a Federal Aviation Administration (FAA) airworthiness inspector. The inspection revealed crankshaft, camshaft, and valve train continuity was confirmed for all cylinders. The magnetos were tightly installed on the engine but the magneto to engine timing was not checked. The "P-Leads" were tightly secured and there was no evidence that a "P-Lead" had grounded. Inspection of the spark plugs revealed that by color they were running lean. Further inspection of the engine revealed the carburetor bowl assembly could be moved by hand pressure in relation to the throttle body assembly. The carburetor (model MA-4SPA) was removed from the engine and sent as found to the National Transportation Safety Board (NTSB) investigator-in-charge for dynamic and teardown inspection. The tachometer time at the time of the accident was recorded to be 781.4 hours.

Inspection of the carburetor was performed at a FAA certified repair station with NTSB oversight. The inspection of it revealed a "Washer-Throttle Body to Bowl Screw" was installed beneath each of the four "Screw-Throttle Body to Bowl." Further inspection of each of the "Screw-Throttle Body to Bowl" revealed 3 of the 4 could be moved by hand, but complete movement of the three loose screws were restricted by the "Washer-Throttle Body to Bowl Screw." The single "Screw-Throttle Body to Bowl" that was tight and could not be moved by hand was installed adjacent to the "L" or lean mark on the flat of the Carburetor Bowl Assembly. Looseness was noted between the Carburetor Bowl Assembly and the Throttle Body Assembly on the side associated with the data plate. No obvious impact damage was noted to any portion of the carburetor. Blue colored fuel stains were noted on the faying surface of the Throttle Body Assembly and also on the Carburetor Bowl Assembly. Blue colored stains were also noted near one Throttle Body to Bowl screw adjacent to the accelerator pump, and adjacent to two Throttle Body to Bowl screws adjacent to the data tag. Each "Washer – Throttle Body to Bowl Screw" was inspected for condition and documented.

Following inspection of the carburetor, it was placed as received on a dynamic test bench that by design applied a down clamping force on the top portion of the carburetor. During the first dynamic test, the accelerator pump worked satisfactory and the fuel flow in terms of pounds-per-hour (PPH) ran richer than specified. Because the test bench equipment applied down clamping force, shims were installed between the carburetor bowl and throttle body assembly. During a second dynamic test with the shims in place, the fuel flow PPH differed slightly from the first test, but was still flowing richer than specified. A copy of the carburetor inspection and bench test results is contained in the NTSB public docket.

A review of the engine maintenance records revealed the carburetor was last overhauled on June 25, 1998, and installed July 6, 1998. There was no record that it had been removed, replaced, or repaired since overhaul. The last annual inspection was signed off as being completed on June 12, 2014; the tachometer time at that time was recorded to be 741.3 hours. At the time of the accident, the airplane had accrued approximately 40 hours since the annual inspection was signed off. Excerpts of the maintenance records are contained in the NTSB public docket.

According to Service Bulletin (SB)-17, dated August 12, 2010, with a subject of, "Body to Bowl Fuel Leaks" indicates there were reports of loose body to bowl joints, with resulting leakage past the gasket between the bowl and throttle body. The SB further indicates that the leakage may be accompanied by loose bowl to throttle body screws. The compliance section of the SB indicates to visually inspect the carburetor for evidence of fuel stains on the outside of the bowl along the throttle body/bowl parting line, and to also check the bowl for looseness relative to the throttle body. The SB goes on to say that if looseness is detected, the carburetor must be removed from the engine and to inspect the threaded holes in the bowl and screws to assure the threads are serviceable. A new gasket and lock tab washers are to be installed, and the carburetor is to be tested in accordance with the appropriate service manual.

NTSB Probable Cause

The loss of engine power during takeoff for reasons that could not be determined during postaccident examination of the engine or testing of the carburetor.