Accident Overview
On September 21, 2015, about 1040 central daylight time, a Cessna 421B airplane, registration N813CA, sustained substantial damage following a loss of engine power and a runway excursion at Platteville Municipal Airport (PBV) in Platteville, Wisconsin. The commercial-rated pilot and a passenger were not injured. The airplane was registered to Blue Hansa LLC and operated by a private individual under 14 Code of Federal Regulations Part 91 as a personal flight. Visual meteorological conditions prevailed, and an instrument flight rules flight plan was filed. The flight was originating at the time of the accident.
Pilot Report
The pilot reported completing a preflight inspection per the checklist and checking the weather. He taxied to the end of runway 15 and performed the pre-takeoff checklist, including an engine run-up for each engine, with no anomalies noted. He taxied onto the runway and advanced both throttles full forward. At 85 knots, just before the runway 7/25 crossing, he initiated rotation and noticed a decrease in right engine manifold pressure and felt a power reduction. He aborted the takeoff by pulling back both throttles and applying the brakes "hard." The airplane continued on the runway for about 1,000 feet, then departed the runway into grass and a soybean field, where it came to rest.
Investigation
The responding Federal Aviation Administration (FAA) inspector documented witness marks left by the accident airplane on the runway and grass surfaces. Tire skid marks were visible on the last 1,000 feet of runway pavement, and tire marks extended into the grass for 290 feet off the end of the runway, where the terrain slopes downward. The tire marks were absent for about 90 feet, consistent with the airplane becoming airborne, until it impacted the ground again and the landing gear collapsed. Witness marks in the grass continued for another 90 feet to where the airplane came to rest in a soybean field.
Runway 15/33 at PBV is 3,999 feet long. The intersection with runway 7/25 is approximately 3,000 feet from the beginning of runway 15, leaving about 1,000 feet of remaining runway from the intersection to the departure end. According to the Cessna 421B operating manual, the distance required for an accelerated stop at a decision speed of 85 knots is about 2,400 feet.
Engine Examination
The right engine was sent to Continental Motors, Inc. in Mobile, Alabama, for examination and an engine test run on January 4 and 5, 2015. The engine was received intact with no signs of significant impact damage. Borescoping revealed normal operating and combustion signatures on cylinders, piston faces, and valve heads. Magneto-to-engine timing was checked, but the exact timing was not determined because it was about 5 degrees past the specified timing scale visible from the engine timing plug.
The engine was mounted on a test stand for functional testing. It started normally on the first attempt with no hesitation in RPM. The propeller was out of track because the propeller flange was bent. Shims were placed between the propeller flange and hub to bring it back into track. The engine was restarted, and RPM was advanced in steps for warm-up. Due to damage to the propeller flange, run time was limited. Throughout testing, the engine accelerated normally without hesitation or interruption in power and demonstrated the ability to produce rated horsepower.