Aircraft collision with residence following propeller separation

Casualties unknown • Marana, AZ, US

An aircraft collided with a tree, wires, and a home after the right propeller began to separate from its mounting flange during takeoff.

What happened

Shortly after takeoff, the pilot was engaged in a flight to transport marijuana contained in duffle bags. During this initial phase of flight, the right propeller began to separate from its mounting flange.

In an attempt to manage the emergency, the pilot turned the aircraft back toward the airport. During the maneuver, the pilot feathered the incorrect propeller and began throwing the duffle bags out of the aircraft. The flight ended when the airplane collided with a tree, utility wires, and a privately owned residence. Two persons inside the residence sustained minor injuries.

The investigation

A post-accident examination of the wreckage provided several mechanical findings. Investigators discovered that the safety wire for the propeller mounting studs was broken. Of the six propeller mounting studs present, three were broken, while the remaining studs had backed off.

Additionally, the right engine oil system showed evidence of extensive metal particles. The investigation also revealed that the propeller governor oil screen had been altered in a manner that allowed unfiltered oil to flow through the system.

Probable cause

The separation of the propeller from its mounting flange was caused by broken and loosened mounting studs, exacerbated by an altered propeller governor oil screen that allowed unfiltered oil flow.

Frequently asked questions

What happened in the 1995-08-30 Piper PA-23-250 accident near Marana, AZ?

An aircraft collided with a tree, wires, and a home after the right propeller began to separate from its mounting flange during takeoff.

What aircraft was involved and where did it happen?

The accident on 1995-08-30 involved a Piper PA-23-250, registration N7156T, at Marana, AZ.

What was the probable cause of the accident?

The separation of the propeller from its mounting flange was caused by broken and loosened mounting studs, exacerbated by an altered propeller governor oil screen that allowed unfiltered oil flow.

Investigation report by the U.S. National Transportation Safety Board (NTSB) historical archive. Original record: https://carol.ntsb.gov/event/20001207X04307. This page is a structured re-presentation; facts and quotes are in the National Transportation Safety Board (NTSB), United States.

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