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Engine Fire During Precautionary Landing Following Manifold Pressure Drop (N21492)

Provo, UT, US

On February 3, 1990, a Piper PA-32RT-300T (registration N21492) operated by Alpine Aviation Inc. was involved in an aviation accident near Provo, UT. No fatalities were reported. Investigators recorded the probable cause as: IMPROPER INSTALLATION BY MAINTENANCE PERSONNEL AND FATIGUE FAILURE AND LEAKAGE OF THE LEFT INTERMEDIATE EXHAUST PIPE, WHICH RESULTED IN AN IN-FLIGHT FIRE IN THE ENGINE COMPARTMENT. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.

Sourcesthe U.S. National Transportation Safety Board (NTSB) historical archivePrimary reportUpdated 2026-07-04Data APIEditorial standards

A pilot experienced a drop in manifold pressure and initiated a precautionary landing. During the base leg, heavy smoke and fumes filled the cabin. After landing, an engine compartment fire was extinguished. Examination revealed a partially separated exhaust pipe at the flange.

Incident Overview

During flight, the pilot noticed a drop in manifold pressure and decided to perform a precautionary landing. While on the base leg to land, heavy smoke and fumes entered the cabin, requiring the pilot to look out of the side vent window to complete the landing. After the aircraft stopped on the runway, a fire in the engine compartment was extinguished.

Examination Findings

An examination revealed that the left intermediate exhaust pipe (Lycoming part number LW-15811) had partially separated at the flange. The engine crossover exhaust assembly had been modified in accordance with AD 89-12-04 and Textron Lycoming Service Bulletin #484, which were intended to prevent this type of failure or separation.

Conclusion

The investigation did not specify a probable cause for the incident. The modifications applied to the engine crossover exhaust assembly were designed to prevent separation of the exhaust pipe at the flange.

In-flight fire & smokeMaintenance errorStructural failure

Frequently asked questions

What happened in the 3 Feb 1990 Piper PA-32RT-300T accident near Provo, UT?

A pilot experienced a drop in manifold pressure and initiated a precautionary landing. During the base leg, heavy smoke and fumes filled the cabin. After landing, an engine compartment fire was extinguished. Examination revealed a partially separated exhaust pipe at the flange.

Were there any fatalities in the 3 Feb 1990 Piper PA-32RT-300T accident?

No fatalities were recorded in this accident.

What aircraft was involved and where did it happen?

The accident on 3 Feb 1990 involved a Piper PA-32RT-300T, registration N21492, operated by Alpine Aviation Inc., at Provo, UT.

What was the probable cause of the accident?

IMPROPER INSTALLATION BY MAINTENANCE PERSONNEL AND FATIGUE FAILURE AND LEAKAGE OF THE LEFT INTERMEDIATE EXHAUST PIPE, WHICH RESULTED IN AN IN-FLIGHT FIRE IN THE ENGINE COMPARTMENT. CONTRIBUTING FACTORS WERE: INADEQUATE SERVICE BULLETIN PROVIDED BY THE MANUFACTURER AND INSUFFICIENT STANDARDS PROVIDED BY THE (FAA)…

More accident analyses

Investigation report by the U.S. National Transportation Safety Board (NTSB) historical archive. Original record: https://carol.ntsb.gov/event/20001212X22549. This page is a structured re-presentation; facts and quotes are in the National Transportation Safety Board (NTSB), United States.