Amateur-built GLASAIR SUPER IIS N8162H accident near Yuma, Arizona

Probable cause

A total loss of engine power as a result of the detachment of the throttle linkage from the throttle arm of the fuel injector servo due to an insufficiently tightened and secured bolt and the subsequent inadequate maintenance inspection.

NTSB analysis

The private pilot reported that, about 35 minutes into the personal cross-country flight, the experimental, amateur-built airplane's alternator field toggle switch/circuit breaker tripped. He reset the switch, and all systems appeared normal. About 5 minutes later, the switch tripped again, and the pilot cycled the switch. About 2 minutes later, the pilot noticed that the engine manifold pressure was dropping, along with the airplane's airspeed, consistent with a partial loss of engine power. The engine then experienced a total loss of power when he was maneuvering for an emergency landing to a nearby airport. The airplane subsequently landed short of the runway and sustained substantial damage to the aft fuselage.

The engine had been installed about 91 flight hours and 5 months before the accident flight, and a condition inspection was completed the same month of installation. Maintenance records indicated that during the period between the engine installation and the accident, maintenance was limited to routine oil changes, magneto timing adjustments, the replacement of exhaust gas temperature and cylinder head temperature probes, and the installation of a replacement alternator.

Postaccident examination of the engine revealed that the throttle linkage had detached from the throttle arm of the fuel injection servo. The rod end bearing for the linkage and the throttle arm were intact and undamaged, but the connecting bolt and its associated washers, castellated nut, and cotter pin were missing. The butterfly valve within the throttle body was in the closed position, and the throttle lever in the cabin was in the full forward (open) position. It is likely that the bolt securing the linkage had not been sufficiently tightened and secured with a cotter pin during the installation and that the error was not detected during the subsequent condition inspection.

The investigation determined that the electrical system malfunction was unrelated to the loss of engine power.

Text from the NTSB. Open the NTSB docket for WPR18LA250 for the full record.