Accident Overview
On May 15, 2016, at approximately 1430 central daylight time, a Piper PA-32R-301 airplane, registration N185DX, was substantially damaged when it impacted terrain following a precautionary landing about 1 mile east of the Alpine-Casparis Municipal Airport (E38) in Alpine, Texas. The private pilot and passenger were not injured. The personal flight was conducted under 14 Code of Federal Regulations Part 91 in visual meteorological conditions. No flight plan had been filed.
Pilot's Account
According to the pilot, he experienced difficulty starting the engine after refueling. He followed the flooded engine start procedures and performed a run-up, checking the magnetos. The engine rpm seemed satisfactory. The takeoff roll from runway 23 (5,018 feet by 60 feet, asphalt) required a good bit of runway. During the climb, the pilot noticed that the exhaust gas temperature (EGT) was pegged. He reversed course to return to the airport. He was unable to find a responsive power setting and adjusted the mixture in an attempt to cool the engine. The pilot stated the engine was not missing. He left the landing gear up and, after clearing powerlines, cut the engine. He performed a gear-up precautionary landing, during which the right wing and fuselage sustained substantial damage.
Engine Examination
An examination of the engine was conducted under the supervision of the National Transportation Safety Board investigator-in-charge. The number six spark plug showed signatures consistent with a lean mixture. The remaining lower spark plugs and engine cylinders had carbon deposits consistent with a rich fuel/air mixture. The flame tubes within the muffler were cracked and deteriorating but remained in place. The EGT was connected via a single probe attached to the number six cylinder; the connection was secure and the probe cable unremarkable. No mechanical anomalies that would have precluded normal operation were found during the external examination.
Engine Test Runs
The engine remained on the airframe, which was secured to a trailer with an external fuel supply. The propeller was impact-damaged with rotational scoring and bending on each blade; it was replaced with a test propeller for the examination. The engine started without hesitation and ran for 15 to 20 minutes at varying power settings. Magnetos and propeller governor checks were normal, achieving 2,700 rpm and 29 to 30 inches of manifold pressure. The investigator noted the EGT was immediately high (near or above peak EGT) and fluctuated at varying power and mixture settings. At higher power settings, the EGT increased to the maximum reading then fell to zero. After shutdown, all six spark plugs appeared darker, consistent with a rich fuel/air mixture. The number six fuel injector was found partially occluded, and the obstruction was removed. A second test run about two hours later showed similar EGT fluctuations: generally high at lower power and spiking then dropping at higher power. No mechanical anomalies were found.
Meteorological Data
Calculations of relevant meteorological data revealed that the density altitude at the time of the accident was 5,750 feet.