Eurocopter Deutschland Gmbh EC135P1 N911KB accident near Shreveport, Louisiana

Probable cause

The mechanic's improper installation of the antitorque pedals, which resulted in an in-flight loss of helicopter control.

NTSB analysis

The helicopter departed on a local maintenance test flight to perform a hover test. The pilot flew the helicopter toward a nearby field to perform the test and then heard a "pop," and the helicopter subsequently began to spin. The pilot attempted to regain control of the helicopter using the antitorque pedals, but they were ineffective. The pilot reduced engine power and performed an autorotation to the field. The helicopter landed hard and rolled on its right side.

Examination of the wreckage found that the antitorque pedals had separated from the antitorque levers. The attachment hardware was not located in the wreckage or the surrounding area. Neither the antitorque pedals nor the lever attachment holes displayed elongation, which is consistent with the hardware bolts not being in place at the time of impact. A review of maintenance logbooks revealed that a mechanic had conducted maintenance on the antitorque pedals 9 days before the accident flight. After the accident, a parts bag containing bolts similar to the bolts needed to secure the antitorque pedals was found in the maintenance facility where the maintenance was performed. Based on the evidence, it is likely that the mechanic reinstalled the antitorque pedals without the required attachment hardware, which allowed the antitorque pedals to separate from the antitorque levers during flight and led to the loss of helicopter control.

Text from the NTSB. Open the NTSB docket for CEN14LA048 for the full record.