Action Follows A Fatal Accident Involving An Enstrom 280FX Helicopter

The FAA has issued an emergency AD for Enstrom Model F-28A, 280, F-28C, F-28C-2, F-28C-2R, 280C, F-28F, F-28F-R, 280F, 280FX helicopters, all serial numbers; and Model 480 helicopters with a serial number (S/N) 5001 through 5006; with a main rotor spindle (spindle), part number (P/N) 28-14282-11 or P/N 28-14282-13.

The action follows a fatal accident that is still under investigation, according to the FAA.

According to the NTSB's preliminary report, A witness reported that the helicopter, an Enstrom 280FX, was on final approach for landing on the runway at what seemed a steep angle of descent. As the helicopter descended, she heard a loud "pop" and the helicopter began to rotate and then the main rotor blades departed off the top of the helicopter. The remainder of the helicopter fell to the ground, impacted, and then "exploded."

Preliminary results indicate that the accident was caused by a crack in the spindle which resulted in the main rotor blade separating from the helicopter. The crack was discovered at the last thread of the spindle retention nut threads. While the investigation could not determine when the crack initiated, it was able to determine that the crack existed, undetected, for a significant amount of time before the separation.

The EAD requires, before further flight, conducting a magnetic particle inspection (MPI) to determine if a crack exists in any spindle that has 5,000 or more hours time-in-service (TIS) or where the hours TIS of the spindle is not known. If there is a crack in the spindle, replacing it before further flight is required. Reporting the inspection results to the FAA is also required within 72 hours. These EAD actions are intended to detect a crack in the spindle which could result in loss of a main rotor blade and subsequent loss of control of the helicopter.

The FAA estimates that this AD affects 323 helicopters of U.S. Registry and that operators may incur the following costs to comply with this AD. Inspecting each spindle will require 15 work-hours at an average labor rate of $85 per work-hour and the cost to report the required inspection information is $43, for a total of $1,318 per helicopter and 425,714 for the U.S fleet.

If replacing a spindle is required, it will take 4 work-hours and $8,164 for parts, for a total of $8,504 per helicopter.

(Image from file. Not accident aircraft)

FMI: EAD