Amateur-built CGS HAWK N5148G accident near Lander, Wyoming

Probable cause

A reported severe airframe vibration and subsequent forced landing for reasons that could not be determined because the wreckage was not made available for examination.

NTSB analysis

The pilot reported that, about 40 minutes after departure at an altitude of about 9,500 ft mean sea level (msl), he decided to land off-airport due to severe up and down shaking of the experimental airplane’s empennage. The pilot reduced the throttle setting and initiated a glide. The pilot observed that the airplane remained stable during the glide, with no extreme vibration, and that he was able to manage the descent smoothly. Shortly after touchdown, the airplane bounced and landed hard on a field. Subsequently, the airplane nosed over and sustained substantial damage to the tail assembly.

The wreckage was recovered from a field onto a flatbed truck by a local resident. The National Transportation Safety Board (NTSB) investigator-in-charge (IIC) interviewed the pilot after the accident and requested that he preserve the wreckage; however, the pilot had given the wreckage to the local resident who helped with the recovery. The pilot added that he was returning to his home country in two weeks when his visa expired. A Federal Aviation Administration (FAA) inspector took pictures of the airplane on top of the flatbed truck but was unable to conduct an examination of the airframe or engine.

The pilot further reported during a follow-up interview that he believed the engine and frame installed were too heavy for the airframe, which resulted in the extreme airframe vibration. He added that the engine was from a pre-owned car and had been installed about 7 years before the accident. The pilot indicated that the violent shaking during the accident sequence was the first occurrence in the airplane's last 204 hours of flight, which spanned the last 90 days. The local resident reported that during the recovery process, the pilot admitted to using zip ties to keep sections of the airplane intact.

The pilot was not responsive after several attempts to coordinate a follow-up examination. Moreover, despite several attempts, the local resident did not respond to the investigator’s request to examine the wreckage. Since the wreckage was not made available for examination, the reason for the reported airframe vibration could not be determined.

Text from the NTSB. Open the NTSB docket for WPR22LA352 for the full record.