McDonnell Douglas MD-520N N520DD
16 May 1996 · Bethany, Oklahoma, United States · No injuries
Summary
On 16 May 1996 at about 20:00 local time, a McDonnell Douglas MD-520N registered N520DD was involved in an accident near Bethany, Oklahoma, United States. 2 people were on board and nobody was injured. The aircraft was substantially damaged. The NTSB has published a probable cause for this accident; it is quoted in full below.
The record
- Date
- at 20:00
- Classification
- Accident
- Location
- Bethany, Oklahoma, United States
- Nearest airport
- Wiley Post (PWA)
- Coordinates
- 35.5001, -97.6409
- Aircraft
- McDonnell Douglas MD-520N
- Registration
- N520DD
- Category
- Helicopter
- Engines
- 1
- Operator
- Not recorded
- Operating rule
- Part 91: General Aviation
- Purpose of flight
- Public Use
- Phase of flight
- Not recorded
- Aircraft damage
- Substantial
- Weather
- VMC
- Light
- Day
- NTSB number
- FTW96TA222
People
Nobody was injured.
| On board | Died | Serious | Minor | Uninjured |
|---|---|---|---|---|
| 2 | 0 | 0 | 0 | 2 |
Probable cause
The main rotor blades' contact with the tail boom due to gusting winds during rotor deceleration.
Quoted verbatim from the NTSB record. This site does not paraphrase or interpret it.
Read the full NTSB narrative
Prior to the landing, the instructor pilot verified the wind from the tower (180 degrees at 19 knots, gusting to 22 knots). With the helicopter stable on the ground, downwind from a nearby building, the flight controls were frictioned down and normal shut down procedures were started. Passing through 19% rotor RPM, the rotor brake was applied. To demonstrate that the rotor would continue turning without rotor brake application, the instructor released the brake at 10% RPM and allowed the rotors to turn down to 9% RPM. The rotor brake was then re-applied, and while the rotor was decelerating, 'two or three thumps were heard', and the instructor observed the rotors 'jerk and come to a stop.' The instructor stated that wind being redirected around the building may have caused the rotors to flap down into the tail boom. Examination of the aircraft revealed that at least two of the three main rotors contacted the tail boom. No mechanical defects were found in the flight control and rotor systems. According to the manufacturer's flight manual, the shut down sequence and rotor brake application were conducted in accordance with current published procedures.
Quoted verbatim from the NTSB record.
Other accidents in this area
| Date | Aircraft | Location | Operator | Outcome | Died |
|---|---|---|---|---|---|
| 12 Jan 1996 | Cessna A188B | Enid, Oklahoma, United States | Carson Flying Service, Inc | No injuries | - |
| 21 Jan 1996 | Cessna 172N | Norman, Oklahoma, United States | - | No injuries | - |
| 3 Feb 1996 | Bell 206B | Cushing, Oklahoma, United States | Corporate Helicopters, Inc. | Serious injuries | - |
| 2 Mar 1996 | Bell B206-BIII | Chandler, Oklahoma, United States | - | Minor injuries | - |
| 18 Apr 1996 | Air Tractor AT-502B | Pond Creek, Oklahoma, United States | Homestead Farms Flying Service | No injuries | - |
| 27 Apr 1996 | Deaton JUNGSTER-1 | McAlester, Oklahoma, United States | - | Serious injuries | - |