Aerospatiale AS365N accident near Valparaiso, Indiana, July 14, 2005
On July 14, 2005 at about 9:04 pm local time, a Aerospatiale AS365N (helicopter), registered N365S, was substantially damaged in an accident near Valparaiso, Indiana (Porter Memorial Hospital airport). It was flown under charter and air-taxi rules (Part 135). No one was hurt; 4 people were on board or involved. The weather was visual conditions (good weather).
The NTSB's probable cause their words, unchanged
The loose tail rotor drive shaft coupling due to its improper installation by the operator's maintenance personnel, which resulted in the failure of the tail rotor drive shaft. An additional cause was the inability of the pilot to maintain control of the helicopter in the hover following the drive shaft failure.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- July 14, 2005 · about 9:04 pm local time
- Place
- Valparaiso, Indiana · Porter Memorial Hospital · map
- Type
- Accident
- Injuries
- No one was hurt; 4 people were on board or involved.
- Weather
- visual conditions (good weather)
- Aircraft
- Aerospatiale AS365N · all AS365Ns on the register
- Registration
- N365S · registry record · serial 6036
- Damage
- Substantial damage
- Flight
- Flight · charter and air-taxi rules (Part 135)
The NTSB's narrative final · quoted from the NTSB record
The helicopter was substantially damaged when it struck the helipad during an uncommanded yaw encountered during the initial hover after liftoff from a roof-top hospital heliport. The pilot reported that he picked up into a 4 to 6-foot hover and initiated a right pedal turn. He stated that as the helicopter reached a west heading "the aircraft would not turn any more" despite his continued application of right pedal. He stated: "As I continued to apply right pedal the aircraft then went into [a] sudden and uncommanded yaw to the left. I was unable to stop the yaw." The helicopter subsequently impacted the helipad and roof structure. It came to rest at the east edge of the helipad oriented on a southeast heading. A post accident inspection revealed that the Fenestron (tail rotor) drive shaft had failed approximately 6 inches aft of the main gearbox. The failure occurred at the point where the drive shaft entered a tunnel formed by the left and right engine firewalls. The firewalls and drive shaft segments in the vicinity of the point of failure exhibited scrape marks. Examination of the forward section of the drive shaft revealed features characteristic of an overload failure. The main gearbox output shaft assembly and rear transmission coupling connected the tail rotor drive shaft to the gearbox. Further examination revealed that the coupling flange could be moved laterally relative to the pinion approximately 3/32 (0.094) inch. Allowable lateral play in the drive flange was 1 millimeter (0.039 inch). Disassembly of the transmission coupling determined that the nut which secured the drive flange to the output assembly pinion gear was improperly installed. Wear patterns indicated that the locking tangs on the cup washer did not engage the corresponding slots on the shaft allowing the nut to loosen over time. In addition, the condition of the locking tangs indicated that they were folded over during installation causing them to separate from the cup. The resulting wear had removed material to such an extent that the contact face was no longer perpendicular to the longitudinal axis of the shaft. This allowed excessive radial play in the transmission coupling, which permitted contact between the tail rotor drive shaft and the firewalls. The FAA Rotorcraft Flying Handbook, FAA-H-8083-21, provided information related to failure of the anti-torque system on a helicopter. The handbook stated: "The loss of antitorque normally results in an immediate yawing of the helicopter's nose. The helicopter yaws to the right in a counter-clockwise rotor system and to the left in a clockwise system. . . . The severity of the yaw is proportionate to the amount of power being used and the airspeed. An antitorque failure with a high power setting at a low airspeed results in a severe yawing." The main rotor system of the accident helicopter rotated clockwise as viewed from above.
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
Pilot
- Certificate: airline transport pilot, flight instructor
- Ratings: multi-engine land; single-engine land; instructor: airplane single-engine; instructor: glider; instructor: helicopter; instructor: instrument airplane; instructor: instrument helicopter; instrument: airplane; instrument: helicopter; rotorcraft: glider; rotorcraft: helicopter
- Flight time: 9,777 hours in all; 667 in this make and model; 45 in the last 90 days; 18 in the last 30 days; 9,617 as pilot in command
- Last flight review: July 1, 2005
- Medical certificate: Class 2 (with waivers/limitations)
- Seat: rgt
- Injury: no injuries
The aircraft
- Airframe total time: 6,268.9 hours
- Last inspection: approved inspection programme, February 1, 2005; 13.8 hours since
- Maximum gross weight: 8,818 lb
- Seats: 4
- Landing gear: retractable
- Engine 1: Turbomeca Arriel 1C (turboshaft); 0 hours total
- Engine 2: Turbomeca Arriel 1C (turboshaft); 0 hours total
- Operator: Cj Systems Aviation Group
The flight
- Departed from: 46II Valparaiso IN at 9:03 pm
- Destination: 4IS3 Chicago IL
- Flight plan: VFR
Weather at the time
- Light: daylight
- Wind: from 360° at 11 knots
- Visibility: 7 statute miles
- Sky: a few clouds at 900 ft
- Temperature: 82°F (28°C), dew point 73°F (23°C)
- Altimeter: 29.90 inHg
- Observation at 8:53 pm from VPZ, 2 miles away
Injuries
| Fatal | Serious | Minor | None | |
|---|---|---|---|---|
| Crew | 3 | |||
| Passengers | 1 |
Documents from the investigation the NTSB's docket: the evidence folder behind the report
The docket, the folder of records gathered during an investigation (maintenance records, photographs, witness statements, examinations), has not been read from the NTSB for this case yet; the list appears here once it has. Open the docket at the NTSB.
Everything on this page comes from the NTSB's public records. The narrative, probable cause and findings are the NTSB's own words; the coded tables behind the report are written out in plain English, with pilots' ages, home towns and medical details left out. The documents and photographs are the NTSB's docket, shown as the NTSB released them. This site's own text never names anyone involved. A preliminary report can change; the final report usually follows one to two years later, and the page is refreshed when it does.