Amateur-built MOOSE accident near Hays, Kansas, September 30, 2011
On September 30, 2011 at about 4:00 pm local time, a amateur-built MOOSE, registered N384JP, was substantially damaged in an accident during enroute (cruise) near Hays, Kansas. It was a personal flight under general aviation rules (Part 91). 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
Rudder flutter due to the design changes to the airplane's horizontal stabilizer.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- September 30, 2011 · about 4:00 pm local time
- Place
- Hays, Kansas · map
- Type
- Accident
- Injuries
- No one was hurt; 4 people were on board or involved.
- Weather
- visual conditions (good weather)
- Aircraft
- Amateur-built MOOSE
- Registration
- N384JP · registry record · serial 303SR
- Damage
- Substantial damage
- Flight
- Personal flight · general aviation rules (Part 91)
The NTSB's narrative final · quoted from the NTSB record
During cruise flight in smooth air, with the autopilot engaged, the experimental category amateur-built airplane suddenly encountered a single occurrence of rudder flutter that lasted 2 to 3 seconds and then ceased. One passenger described the “frequency of vibration about 10 Hz” (cycles per second) and described the sound as “BRAAP.” The pilot disengaged the autopilot and continued to his original destination for an uneventful landing. A subsequent examination of the airplane found substantial damage to the stringers, frames, and empennage skin in the area just forward of the horizontal stabilizers. The pilot, who was also the builder of the airplane, had added an electrically actuated rudder trim tab several years earlier. Most of the weight of the rudder assembly was aft of the rudder hinges, and the builder had not installed rudder counterbalance weights forward of the hinges. In addition, he had recently installed struts on the bottom of the horizontal stabilizer. Airworthiness standards for certification of normal category airplanes require that they must be shown to be free from flutter. Airworthiness standards for certification of experimental category airplanes do not require that they meet those standards.
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
- Miscellaneous/other during prior to flight
- Miscellaneous/other during enroute (cruise)
- Flight control sys malf/fail during enroute (cruise) defining event
The NTSB's findings
- cause Aircraft › Aircraft oper/perf/capability › Performance/control parameters › (general) › Capability exceeded
- cause Aircraft › Aircraft systems › Flight control system › Rudder tab control system › Design
- cause Aircraft › Aircraft structures › Empennage structure › Horizontal stabilizer › Design
- cause Aircraft › Aircraft structures › Empennage structure › (general) › Capability exceeded
Pilot
- Certificate: private
- Ratings: single-engine land; instrument: airplane
- Flight time: 1,130 hours in all; 516 in this make and model; 54 in the last 90 days; 7 in the last 30 days; 1,137 as pilot in command; 0 on instruments
- Last flight review: July 18, 2009
- Medical certificate: Class 3 (with waivers/limitations)
- Seat: left
- Injury: no injuries
The aircraft
- Airframe total time: 401 hours
- Last inspection: condition inspection, April 1, 2011; 67 hours since
- Maximum gross weight: 3,500 lb
- Seats: 4
- Landing gear: fixed
- Engine: Voronezh M14P (piston); 0 hours total
The flight
- Departed from: 18V Hudson CO at 1:40 pm
- Destination: HYS Hays KS
Weather at the time
- Light: daylight
- Visibility: 50 statute miles
- Sky: clear
- Temperature: 70°F (21°C), dew point 0°F (-18°C)
- Altimeter: 30.37 inHg
Injuries
| Fatal | Serious | Minor | None | |
|---|---|---|---|---|
| Flight crew | 1 | |||
| Passengers | 3 |
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.