The flight instructor reported that while he and the student pilot were on a taxiway in Anchorage, Alaska, under air traffic control (ATC) instruction, the Cessna 172 encountered prop wash, originating from a larger, four engine turbine-powered airplane performing a maintenance engines run-up.
The maintenance run-up was performed in a location adjacent to the active taxiway that was authorized for parking as well as 80% engine power run-ups.
The larger turbine-powered airplane was the third in a row a five of like model airplanes being parked at the location.
The Cessna 172 was not on frequency when the larger turbine-powered airplane was given the clearance, and was not told by ATC at any time during their taxi of the larger turbine-powered airplane’s intentions.
Subsequently, the 172 was blown approximately 80′ from its original location while taxing behind the larger turbine-powered airplane, which resulted in substantial damage to the firewall.
The flight instructor reported that there were no pre impact mechanical failures or malfunctions with the airframe or engine that would have precluded normal operation.
As a safety recommendation the flight instructor stated that the incident could have been prevented with better communications between the tower controllers and the larger turbine-powered airplane’s ground personnel.
Probable cause: The facility’s designation of the taxiway for use by maintenance personnel to conduct high thrust tests without appropriate safeguards in place, which led to maintenance personnel conducting high-power, run-up thrust procedures across the active taxiway and resulted in the loss of directional control of a Cessna 172 on the taxiway when it encountered a sudden, unexpected blast of engine thrust.
NTSB Identification: GAA16CA442
This August 2016 accident report is provided by the National Transportation Safety Board. Published as an educational tool, it is intended to help pilots learn from the misfortunes of others.