Eurocopter Deutschland GMBH MBB-BK 117 C-2 accident near West Lafayette, Indiana, March 7, 2024
On March 7, 2024 at about 2:40 am local time, a 2009 Eurocopter Deutschland GMBH MBB-BK 117 C-2 (helicopter), registered N191LL, was substantially damaged in an accident during taxi (to runway) near West Lafayette, Indiana (Purdue University airport). It was a positioning flight under charter and air-taxi rules (Part 135). No one was hurt; 3 people were on board or involved. The weather was visual conditions (good weather).
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The NTSB's probable cause their words, unchanged
The failure of maintenance personnel to properly install the tail rotor pitch change slider attachment hardware (T-bolt), which led to the disconnection of the pitch change slider, a loss of tail rotor control, and subsequent hard landing. Contributing to the accident was maintenance personnel’s failure to complete a maintenance discrepancy entry on the work order for the removal of the T-bolt.
Source: NTSB aviation accident database, copy made October 4, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- March 7, 2024 · about 2:40 am local time
- Place
- West Lafayette, Indiana · Purdue University · map
- Type
- Accident
- Injuries
- No one was hurt; 3 people were on board or involved.
- Weather
- visual conditions (good weather)
- Aircraft
- Eurocopter Deutschland GMBH MBB-BK 117 C-2, built 2009
- Registration
- N191LL · registry record · serial 9319
- Damage
- Substantial damage
- Flight
- Positioning flight · charter and air-taxi rules (Part 135)
The NTSB's narrative final · quoted from the NTSB record
The pilot reported that while in a hover taxi to accelerate for takeoff, he felt a force against his feet from the pedals and the helicopter began to yaw to the right. The pilot was unable to arrest the right yaw with pedal inputs. The helicopter landed hard, which resulted in substantial damage to the fuselage, tailboom, vertical fin, horizontal stabilizer, tail rotor assembly, and one main rotor blade. Postaccident examination revealed that the T-bolt and its attachment bolts, which connects the pitch change bellcrank to the pitch change slider, became disconnected during operation due to inadequate installation. Specifically, the T-bolt attachment bolts were installed but not torqued and safety wired to maintenance manual requirements, allowing them to back out during operation. Once the T-bolt attachment bolts backed out, the T-bolt also backed out and separated from the pitch change slider, resulting in a loss of tail rotor pitch control. The T-bolt likely impacted one of the tail rotor blades, resulting in the separation of the outboard portion of its leading edge and afterbody. The subsequent imbalance of the tail rotor, due to the damaged tail rotor blade, led to overload separation of the upper portion of the vertical fin. During maintenance of the accident helicopter in the days leading up to the accident, the T-bolt and its attachment bolts were removed by a mechanic at the direction of a lead mechanic to facilitate troubleshooting of adjacent components for the tail rotor control system. That mechanic assumed that the T-bolt’s removal was temporary and quick, so he did not follow established procedures by recording the removal in the discrepancy sheet for the work order. The T-bolt attachment bolts were subsequently temporarily installed “finger-tight” by another mechanic to assist a mechanic who was installing the tail rotor blade mounting forks and pitch change links. However, the first mechanic was tasked to another company helicopter shortly after, and while he stated he relayed to the other mechanics that the T-bolt attachment bolts were finger-tight, no one followed up on the installation of the T-bolt attachment bolts to ensure they were torqued correctly and safety wired. Additionally, no one from the maintenance team found that the safety wiring for the T-bolt attachment bolts was missing during final checks of the helicopter before it was released for an operational check flight. Since there was no maintenance discrepancy entry for the removal of the T-bolt, there was no formalized task for the maintenance team to track and verify the complete T-bolt installation, including torquing and safety wiring the T-bolt attachment bolts. Therefore, the lack of an entry in the work order discrepancy sheet for the T-bolt’s removal contributed to this accident.
The complete narrative as the NTSB published it. The NTSB's docket holds the report as a PDF and any photographs, statements and other documents from the investigation.
The factual record from the NTSB's investigation tables, in plain English
What happened, in order
- Loss of control in flight during taxi (to runway)
- Part(s) separation from AC during taxi (to runway) defining event
The NTSB's findings
- Personnel issues › Task performance › Maintenance › Installation › Maintenance personnel
- Personnel issues › Action/decision › Action › Incomplete action › Maintenance personnel
- Personnel issues › Task performance › Record › keeping › Aircraft/maintenance logs › Maintenance personnel
- Aircraft › Aircraft systems › Flight control system › (general) › Incorrect service/maintenance
Pilot
- Certificate: airline transport pilot
- Ratings: instructor: helicopter; instrument: helicopter; rotorcraft: helicopter
- Flight time: 6,266 hours in all; 566 in this make and model; 36 in the last 90 days; 18 in the last 30 days; 4,666 as pilot in command; 2,032 on instruments
- Last flight review: November 8, 2023
- Medical certificate: Class 1 (with waivers/limitations)
- Seat: rgt
- Injury: no injuries
The aircraft
- Airframe total time: 7,434.5 hours
- Last inspection: approved inspection programme, March 6, 2024
- Maximum gross weight: 7,904 lb
- Seats: 5
- Landing gear: fixed
- Engine 1: Safran Arriel 1E2 (turboshaft); 5,027 hours total
- Engine 2: Safran Arriel 1E2 (turboshaft); 4,040 hours total
- Operator: Metro Aviation
The flight
- Destination: Monticello IN
Weather at the time
- Light: night
- Wind: from 060° at 9 knots, gusting 16
- Visibility: 10 statute miles
- Sky: overcast at 2,100 ft; a few clouds
- Temperature: 46°F (8°C), dew point 39°F (4°C)
- Altimeter: 30.06 inHg
- Observation at 9:54 pm from KLAF
Weather report (METAR): KLAF 070254Z AUTO 06009G16KT 10SM OVC021 08/04 A3006 RMK AO2 SLP182 T00830039 53014
Injuries
| Fatal | Serious | Minor | None | |
|---|---|---|---|---|
| Cabi | 2 | |||
| Flight crew | 1 |
Documents from the investigation the NTSB's docket: the evidence folder behind the report
15 documents, released by the NTSB on April 24, 2025. View them here, or download them; the NTSB redacts some personal details before release, and this site shows the NTSB's own titles rather than its file names.
The same docket at the NTSB · documents without a copy here are fetched from the NTSB when you open them.
About this page
Everything above comes from the NTSB's public accident database: the narrative, probable cause and findings are the NTSB's own words, and the coded tables behind its report (pilot, aircraft, flight, weather, injuries, sequence of events) are written out in plain English. Pilots' ages, home towns and medical details are left out on purpose. The documents and photographs are the NTSB's docket, the folder of records gathered during the investigation, shown as the NTSB released them (the NTSB redacts some personal details first) and listed under the NTSB's own titles. This site's own text never names pilots, passengers or anyone else involved. A preliminary report describes what is known soon after the event and can change; the final report, with the probable cause, usually follows one to two years later and this page is refreshed when it does. Case number CEN24LA128.