Writer

Amy Wilder

Improper T-bolt installation and maintenance records were <a href="https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/193891/pdf">cited by the NTSB</a> as the probable cause in a March 2024 air ambulance accident in Indiana. The Airbus Helicopters BK117C2 sustained substantial damage during a “hard landing” after a critical tail rotor control failure. Two medical crewmembers aboard, as well as the pilot,&nbsp;were not injured in the mishap.
Operating as an air ambulance under Part 135, the helicopter was departing Purdue University Airport (KLAF) in West Lafayette, Indiana, at night when the pilot reported feeling a sudden force on the pedals during a hover taxi. The aircraft began an uncommanded right yaw, and the pilot stated that left pedal input had no effect. Next, the pilot executed an emergency landing.
An examination revealed that the T-bolt connecting the tail rotor pitch change bellcrank to the pitch change slider had separated in flight. The NTSB found that the T-bolt and its attachment bolts had been removed “at the direction of a lead mechanic to facilitate troubleshooting of adjacent components,” after which maintenance personnel temporarily installed the T-bolt attachment bolts “finger-tight” without torquing or safety wiring them as required.
Maintenance records did not include any entry for the T-bolt’s removal or reinstallation, and no verification of its final installation was performed before the aircraft was returned to service. The NTSB concluded that the lack of documentation contributed to the oversight.
One bolt was found on the ramp after the accident, and another had struck the engine bay. The second bolt was found “lodged into a honeycomb panel at the aft-lower area of the fuselage, adjacent to the fuel cell.”

News about significant aircraft accidents and information from accident reports.

NTSB: Improper T-bolt Install Led to Indiana EMS Eurocopter BK117 Accident

No injuries reported after the air ambulance accident

A Eurocopter BK117 sustained damage during a hard landing after a tail rotor failure. NTSB identified the probable cause as improperly installed hardware.

NTSB Cites Faulty T-bolt Install in Tail Rotor Failure

2024 Corporate Aviation Leadership Summit

News and issues relating to business, corporate and private aviation, primarily regarding turbine-engine-powered airplanes and helicopters. Subjects include aircraft, engines, maintenance, operations, personnel, acquisitions, accidents, safety, security, and training.

Sound Talent Group confirmed three employee fatalities

Music Agent Shapiro among Six Killed in Citation Crash

News and information on safety procedures and concerns.

News and issues relating to the aerospace industry that are related to the science, engineering and business of flight in space involving civil, industrial and military applications, and similar topics related to flight in the atmosphere of the Earth that are not covered more directly by other AINonline subject channels. In other words, both astronautical and aeronautical subjects, except for those aeronautical topics that are specifically covered elsewhere on this website.

Air Force intercept confirmed no cockpit or cabin activity before crash

Known Oxygen System Deficiency Preceded Fatal Crash

News and issues concerning general aviation, specifically airplanes and helicopters powered by piston and alternative engines (i.e., non-turbine powered aircraft). Subjects include aircraft, engines, personnel, acquisitions, accidents, safety, security and training.

Flight continued under VFR despite known radio altimeter issue

VFR into IMC, Poor Preflight, and ADM Led to Helo Crash

Kerry Lynch

 Woman succumbs to injuries three months after accident

Philadelphia Learjet Crash Claims Eighth Victim

Matt Thurber

News and issues relating to international air transport and cargo carriers, national airlines and regional airlines, including aircraft, engines, personnel, acquisitions, accidents, safety, security and training.

More In Accidents

Music Agent Shapiro among Six Killed in Citation Crash

Sound Talent Group confirmed three employee fatalities

Known Oxygen System Deficiency Preceded Fatal Crash

Air Force intercept confirmed no cockpit or cabin activity before crash

VFR into IMC, Poor Preflight, and ADM Led to Helo Crash

Flight continued under VFR despite known radio altimeter issue

Philadelphia Learjet Crash Claims Eighth Victim

Woman succumbs to injuries three months after accident

AINsight: It’s Time To Put Video Recorders in Cockpits

More data is needed, and there’s only one way to get it

Business Aircraft Accident Reports: May 2025

Preliminary and final accident reports, May 2025

Deicing Omission Led To Embraer Phenom 300 Crash in Utah

Pilot didn't obtain deicing services or properly inspect wing surfaces, says safety agency

NTSB Cites Cable Misrouting in Beechcraft 400A Crash

Two occupants suffered minor injuries in runway overrun and gear collapse

AIN Products

SUBSCRIPTIONS

RESOURCES

ABOUT AIN