Individually Owned: 150,657
Corporate Owned: 137,281
Aircraft Accident/Incident Report
Hays, Kansas 67601
Friday, September 30, 2011 11:00 CDT
NTSB Narrative Summary Released at Completion of Accident
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.
NTSB Probable Cause Narrative
Rudder flutter due to the design changes to the airplane's horizontal stabilizer.
Event Information
| Type of Event | Accident |
| Event Date | 9/30/2011 |
| Event Day of the Week | Friday |
| Time of Event | 1100 |
| Event Time Zone | Central Daylight Time |
| Event City | Hays |
| Event State | KANSAS |
| Event Country | -- |
| Zipcode of the event site | 67601 |
| Event Date Year | 2011 |
| Event Date Month | 9 |
| MidAir Collision Indicator | No |
| On Ground Collision occurred ? | No |
| Event Location Latitude | 385019N |
| Event Location Longitude | 0991614W |
| Event Location Airport | -- |
| Event Location Nearest Airport ID | -- |
| Indicates whether the acc/inc occurred off or on an airport | Off Airport/Airstrip |
| Distance from airport in statute miles | -- |
| Degrees magnetic from airport | -- |
| Airport Elevation | -- |
| Weather Briefing Completeness | -- |
| Investigator's weather source | Pilot |
| Time of the weather observation | |
| Direction of event from weather observation facility (degrees) | -- |
| Weather Observation Facility ID | -- |
| Elevation of weather observation facility | -- |
| Distance of event from weather observation facility (units?) | -- |
| Time Zone of the weather observation | CDT |
| Lighting Conditions | Day |
| Lowest Ceiling Height | -- |
| Lowest Non-Ceiling Height | -- |
| Sky/Lowest/Cloud Conditions | Clear |
| Sky Condition for Lowest Ceiling | None |
| Visibility Runway Visual Range (Feet) | -- |
| Visibility Runway Visual Value (Statute Miles) | -- |
| Visibility (Statute Miles) | 50 |
| Air Temperature at event time (in degrees celsius) | 21 |
| Dew Point at event time (in degress fahrenheit) | -- |
| Wind Direction (degrees magnetic) | -- |
| Variable Wind Indicator | -- |
| Wind Speed (knots) | -- |
| Wind Velocity Indicator | Calm |
| Wind Gust Indicator | -- |
| Wind Gust (knots) | -- |
| Altimeter Setting at event time (in. Hg) | 30.38 |
| Density Altitude (feet) | -- |
| Intensity of Precipitation | -- |
| METAR weather report | -- |
| Event Highest Injury | None |
| On Ground, Fatal Injuries | -- |
| On Ground, Minor Injuries | -- |
| On Ground, Serious Injuries | -- |
| Injury Total Fatal | -- |
| Injury Total Minor | -- |
| Injury Total None | 4 |
| Injury Total Serious | -- |
| Injury Total All | -- |
| Investigating Agency | NTSB |
| NTSB Docket Number (internal use) | 29393 |
| NTSB Notification Source | FAA ACE Regional Operations Ce |
| NTSB Notification Date | -- |
| NTSB Notification Time | -- |
| Fiche Number and/or location -used to find docket information | -- |
| Date of most recent change to record | Feb 1 2012 12:11PM |
| User who most recently changed record | johb |
| Basic weather conditions | Visual Meteorological Cond |
| FAA District Office | -- |
Aircraft Involved |
|
|---|---|
Aircraft #1 |
|
| Aircraft Registration Number | N384JP |
| NTSB Number | CEN11CA679 |
| Missing Aircraft Indicator | -- |
| Federal Aviation Reg. Part | Part 91: General Aviation |
| Type of Flight Plan filed | Company VFR |
| Flight plan Was Activated? | Yes |
| Damage | Substantial |
| Aircraft Fire | None |
| Aircraft Explosion | None |
| Aircraft Manufacturer's Full Name | WALTMAN THEODORE J |
| Aircraft Model | MOOSE |
| Aircraft Series Identifier | -- |
| Aircraft Serial Number | 303SR |
| Certified Max Gross Weight | 3500 |
| Aircraft Category | Airplane |
| Aircraft Registration Class | -- |
| Aircraft is a homebuilt? | Yes |
| Flight Crew Seats | 2 |
| Cabin Crew Seats | -- |
| Passenger Seats | -- |
| Total number of seats on the aircraft | 4 |
| Number of Engines | 1 |
| Fixed gear or retractable gear | Fixed |
| Aircraft, Type of Last Inspection | Conditional |
| Date of Last Inspection | Apr 1 2011 12:00AM |
| Airframe hours since last inspection | 67 |
| Airframe Hours | 401 |
| ELT Installed | Yes |
| ELT Activated | No |
| ELT Aided Location of Event Site | No |
| ELT Type | C91-A |
| Aircraft Owner Name | THEODORE J WALTMAN |
| Aircraft Owner Street Address | -- |
| Aircraft Owner City | LAKEWOOD |
| Aircraft Owner State | CO |
| Aircraft Owner Country | USA |
| Aircraft Owner Zipcode | 80227-4049 |
| Operator is an individual? | Yes |
| Operator Name | THEODORE J WALTMAN |
| Operator Same as Owner? | Yes |
| Operator Is Doing Business As | -- |
| Operator Address Same as Owner? | Yes |
| Operator Street Address | -- |
| Operator City | LAKEWOOD |
| Operator State | CO |
| Operator Country | USA |
| Operator Zip code | 80227-4049 |
| Operator Code | -- |
| Owner has at least one certificate | None |
| Other Operator of large aircraft? | No |
| Certified for Part 133 or 137 Operation | -- |
| Operator Certificate Number | -- |
| Indicates whether an air carrier operation was scheduled or not | -- |
| Indicates Domestic or International Flight | -- |
| Operator carrying Pax/Cargo/Mail | -- |
| Type of Flying (Per_Bus / Primary) | Personal |
| Second Pilot on Board | No |
| Departure Point Same as Event | No |
| Departure Airport Code | 18V |
| Departure City | Hudson |
| Departure State | CO |
| Departure Country | USA |
| Departure Time | 740 |
| Departure Time Zone | MDT |
| Destination Same as Local Flt | -- |
| Destination Airport Code | HYS |
| Destination City | Hays |
| Destination State | KS |
| Destination Country | USA |
| Specific Phase of Flight | -- |
| Report sent to ICAO? | -- |
| Evacuation occurred | -- |
| Date of most recent change to record | Nov 28 2011 12:43PM |
| User who most recently changed record | latt |
| Since inspection or accident | Time of Accident |
| Event Location Runway Number and Location | N/A |
| Runway Length | -- |
| Runway Width | -- |
| Sight Seeing flight | No |
| Air Medical Flight | No |
| Medical Flight | -- |