Ott 601XL-B N610TT

Summary

On 31 March 2017 at about 23:55 local time, a Ott 601XL-B registered N610TT was involved in an accident near The Dalles, Oregon, United States. 2 people were on board and 2 had minor injuries. The aircraft was substantially damaged. The NTSB has published a probable cause for this accident; it is quoted in full below.

Date

31 March 2017 at 23:55

Classification

Accident

Location

The Dalles, Oregon, United States

Nearest airport

Columbia Gorge Regional/The Da (DLS)

Coordinates

45.6181, -121.1675

Aircraft

Ott 601XL-B

Registration

N610TT

Category

Airplane

Year built

2012

Engines

1

Operator

Not recorded

Operating rule

Part 91: General Aviation

Purpose of flight

Personal

Phase of flight

Not recorded

Route

The Dalles → The Dalles

Aircraft damage

Substantial

Weather

VMC

Light

Day

NTSB number

WPR17LA082

2 people had minor injuries.

A partial loss of engine power due to the reverse bending fatigue failure of the propeller hub bolts, which resulted from the bolts not fitting tightly into the propeller hub holes. Also causal was the pilot's decision to use improper bolts for this type of installation/operation.

Quoted verbatim from the NTSB record. This site does not paraphrase or interpret it.

Read the full NTSB narrative

The commercial pilot, who was also the owner/builder of the experimental amateur-built airplane, reported that, after departure and while climbing through 3,500 ft mean sea level, he heard the engine sound abruptly change and observed a loss of rpm and higher-than-normal exhaust gas temperature readings. The pilot turned back toward the airport and attempted to troubleshoot the problem; however, the airplane continued to produce less power than expected. The pilot established a normal traffic pattern for the runway. After turning to final, the airplane started descending and had insufficient power to reach the runway. The airplane subsequently impacted terrain short of the runway. Postaccident examination of the airplane revealed that all six propeller bolts that held the propeller hub to the drive hub were fractured. Further examination of the bolts revealed that the fracture surfaces all exhibited similar features consistent with reverse bending fatigue, likely from not fitting tightly into the propeller hub holes. The pilot reported that he had converted the engine and that, given its unique conversion, the bolts that were typically used to connect the propeller hub to the drive hub were too short; therefore, he chose to use the bolts that were on the hub at the time of the accident. Given the condition of the bolts and the pilot's statement, it is likely the bolts did not fit tightly in the propeller hub holes, which led to their failure due to reverse bending fatigue.

Quoted verbatim from the NTSB record.