ANC02FA064

NTSB accident investigation · Denzer RAF 2000 · Palmer, AK · June 29, 2002

Accident · FatalField investigationFinal report
Date
June 29, 2002, 09:48 local (17:48 UTC)
Place
Palmer, AK
Injuries
1 fatal
Damage
Substantial damage
Phase of flight
Takeoff
Aircraft
N435PRDenzer RAF 2000
Weather
Visual (VMC) · Day
Status
Completed · report April 23, 2003
Report
Approved by Office Director
NTSB office
Alaska Regional Office
Parties
FAA-AL-ANC FSDO 03
FAA report
20020629016839A
Case key
55101

From the NTSB’s public API. By law, NTSB reports can’t be used as evidence in lawsuits over the accident.

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Probable cause

The pilot's abrupt liftoff during takeoff, and his failure to correct a pilot-induced-oscillation during takeoff initial climb which resulted in the main rotor blades striking the tail mounted rudder, and an in-flight loss of control. A factor in the accident was the pilot's lack of recent experience in a gyroplane.

Sequence of events

NTSB’s coding before 2008: each occurrence and phase of flight, and the causes and factors under it. The codes are defined in NTSB’s coding manual.

Abrupt maneuverTakeoff
Lift-off - abruptPilot in commandCause
Rotor system,main rotor blade - blade strike
Airport facilities,runway/landing area condition - runway
Loss of control - in flightTakeoff - initial climb
Lack of recent experiencePilot in commandFactor
Porpoise/pilot-induced oscillation - not correctedPilot in commandCause
Misc rotorcraft,main rotor/tail boom contact - blade strike
Physiological conditionPilot in command
In flight collision with terrain/waterDescent - uncontrolled
Terrain condition - runway

Analysis

The private airplane pilot was conducting touch and go landings in a two-seat, wheel-equipped experimental/homebuilt gyroplane. During the takeoff roll, the gyroplane lifted off abruptly, and the main rotor blades struck the runway surface near the location where the gyroplane lifted off. The gyroplane then climbed steeply to an altitude of less than 100 feet above the ground, and went through one or more longitudinal axis pitch oscillations. The main rotor was observed to slow down and strike the tail-mounted rudder. The gyroplane then descended to the runway in a steep nose-down attitude. Examination of the wreckage revealed no evidence of any preexisting mechanical anomalies. The gyroplane kit was purchased by the pilot in April, 2000. It was assembled by the pilot/owner in Alaska, and transported to Alabama in January, 2002. The pilot began receiving flight training in the gyroplane on January 16, 2002, and concluded training on February 2, 2002. On February 3, 2002, the pilot completed an application for a private pilot, rotorcraft gyroplane rating, and the application was endorsed by the pilot's flight instructor. According to the pilot's flight instructor, the pilot planned to travel from Alabama to Alaska, and planned to complete the practical (flight) test portion of the gyroplane rating either enroute or in Alaska. Application for an additional gyroplane rating requires that the applicant accumulate at least 40 hours of flight time that includes at least 20 hours of flight training, and 10 hours of solo flight, and complete a practical test. No additional written test is required. On the application, the pilot listed 42.4 hours in a gyroplane, 32.2 hours of instruction, and 10.2 hours of solo flight. The pilot did not complete the practical test for a rotorcraft gyroplane rating. His last flight in the gyroplane was four months before the accident. A postmortem examination of the pilot attributed the cause of death for the pilot to blunt force injuries. Additionally, the examination found severe (60 to 70 percent) occlusive arteriosclerotic cardiovascular disease. The FAA's Rotorcraft Flying Handbook contains a discussion of pilot-induced oscillation (PIO), and power pushover situations. The handbook notes that gyroplanes experience a slight delay between control input and the reaction of the aircraft. This delay may cause an inexperienced pilot to apply more control input than required, resulting in a greater aircraft response than was desired. Once the error has been recognized, opposite control input is applied to correct the flight attitude. Because of the nature of the delay in aircraft response, it is possible for the corrections to be out of synchronization with the movements of the aircraft and aggravate the undesired changes in attitude. The result is pilot-induced oscillations that can grow rapidly in magnitude. A power pushover, as described in the FAA handbook, may result if rotor force is rapidly removed, producing a tendency to pitch forward abruptly. This is often referred to as a forward tumble, buntover, or power pushover. Removing the rotor force is often referred to as unloading the rotor, and can occur if pilot-induced oscillations become excessive. A power pushover can occur on some gyroplanes that have the propeller thrust line above the center of gravity and do not have an adequate horizontal stabilizer. In this case, when the rotor is unloaded, the propeller thrust magnifies the pitching moment around the center of gravity. This nose pitching action could become self-sustaining and irreversible.

Factual narrative

History of flight

On June 29, 2002, about 0948 Alaska daylight time, a wheel-equipped experimental/homebuilt Denzer RAF 2000 gyroplane, N435PR, sustained substantial damage when it collided with the paved runway surface following a loss of control during initial takeoff climb at the Palmer Municipal Airport, Palmer, Alaska. The gyroplane was being operated as a Title 14 CFR, Part 91 visual flight rules (VFR) local area personal flight when the accident occurred. The gyroplane was operated by the pilot. The private certificated airplane pilot, the sole occupant, received fatal injuries. Visual meteorological conditions prevailed, and no flight plan was filed. The flight originated from the Palmer Airport about 0930.

At 0924, the pilot contacted the Federal Aviation Administration (FAA) flight service station specialist at the Palmer Airport via radio. The pilot reported he was at the transient apron, and requested traffic advisories. The flight service specialist indicated the winds were light and variable, southeasterly, 130 degrees at 6 knots.

About 0930, the pilot radioed that he was ready to depart runway 16. The gyroplane was observed by the flight service station specialist, and several witnesses around the airport, to conduct two touch and go landings on runway 16. About 0941, the pilot radioed that he was extending his downwind pattern, and was number two behind landing traffic. At 0942, the pilot reported he was on final approach for landing on runway 16.

Following the third landing, ground witnesses observed the gyroplane lift off abruptly, climb steeply to an altitude of less than 100 feet above the ground, and then nose over and descend. One witness reported hearing "popping" sounds, and then observed the gyroplane in a steep descent. Other witnesses said the gyroplane went through one or more longitudinal axis pitch oscillations. They saw the main rotor slow down and strike the tail-mounted vertical stabilizer and rudder. The gyroplane then descended to the runway in a steep nose-down attitude.

A fixed-based operator at the Palmer Airport utilizes a wide-angle video camera, along with a video recorder, to observe the activity around the business. The camera is pointed toward the south. The operator provided a copy of their video tape to the National Transportation Safety Board (NTSB) investigator-in-charge (IIC) for review. An examination of the video recording revealed that during play-back, it ran at twice normal speed. A barely visible, distant image of the gyroplane was observed on the recording entering the left side of the video screen. The gyroplane made an arching climb and descent path from the runway to impact on the runway.

Personnel information

The pilot held a private pilot certificate with an airplane single-engine land rating that was issued on August 29, 1999. The most recent third-class medical certificate was issued to the pilot on August 15, 2000, and contained the limitation that the pilot shall possess glasses that correct for near vision.

The pilot transported the accident gyroplane, via trailer, to Brewton, Alabama, where he began receiving flight training on January 16, 2002, and concluded training on February 2, 2002. On February 3, 2002, the pilot completed an application for an additional private pilot rating, rotorcraft gyroplane, and the application was endorsed by the pilot's flight instructor. Application for an additional gyroplane rating requires that the applicant accumulate at least 40 hours of flight time that includes at least 20 hours of flight training, and 10 hours of solo flight, and complete a practical (flight) test. No additional written test is required. On the application, the pilot listed 42.4 hours in a gyroplane, 32.2 hours of instruction, and 10.2 hours of solo flight.

According to the pilot's flight instructor, the pilot planned to return to Alaska with the gyroplane via trailer, and planned to complete the practical test portion of the gyroplane rating from a gyroplane examiner, either en route, or after reaching Alaska.

According to the pilot's logbook, his total aeronautical experience consisted of about 204 hours, of which 160 hours were accrued in airplanes, and 44 hours in the accident gyroplane. The last flight the pilot logged in the accident aircraft was on February 28, 2002.

The FAA has no record of the pilot taking a practical test for a gyroplane rating.

The pilot held a repairman certificate with an experimental aircraft builder rating for the accident aircraft. It was issued on June 2, 2002 by FAA personnel from the Anchorage Flight Standards District Office.

Aircraft information

The RAF 2000 gyroplane design is comprised of a T-shaped box-beam airframe with tricycle gear, a two-seat enclosed cockpit, and a free spinning two-bladed rotor attached at the top of a mast. The gyroplane is equipped with a pre-rotator drive. Behind the seat is an aft-facing gasoline powered, water-cooled, 4 cycle automotive engine modified for use in the gyroplane. The engine is equipped with a three-bladed composite pusher propeller. A vertical tail and rudder, along with about a 6-inch diameter tailwheel, is attached at the aft end of the airframe beam, behind the engine assembly.

The gyroplane kit was purchased by the pilot in March, 2000. It was completed by the pilot in Alaska in August 2001, and registered by the pilot with the FAA on September 19, 2001. The gyroplane was transported to Alabama in January, 2002, via trailer, for the purpose of training.

Examination of the gyroplane's amateur-built aircraft log book revealed that the pilot certified the aircraft as having been inspected in accordance with the scope and detail of Appendix D, CFR Part 43, on January 7, 2002.

The gyroplane was issued a Certificate of Airworthiness on January 9, 2002, by an FAA Designated Airworthiness Representative (DAR) in Alabama. The DAR requested that the FAA issue the pilot/owner a repairman certificate. On the same date, the aircraft was also issued Phase I and Phase II Experimental Operating Limitations by the DAR.

At the time of the accident, the gyroplane had accumulated a total time in service of 56.9 hours.

Meteorological information

At 0953, an Aviation Routine Weather Report (METAR) at Palmer was reporting, in part: Wind, variable at 4 knots; visibility, 10 statute miles; clouds and sky condition, few at 7,500 feet; temperature, 59 degrees F; dew point, 48 degrees F; altimeter, 29.54 inHg.

Communications

The pilot communicated with the inflight position of the Palmer Flight Service Station (FSS).

A transcript of the air to ground communications between the gyroplane and the Palmer FSS facility is included in the public docket of this accident.

Aerodrome and ground facilities

The Palmer Airport is equipped with a hard-surfaced runway on a 160/340 degree magnetic orientation (runway 16/34), a parallel gravel-surfaced runway on a 140/320 degree magnetic orientation (runway 14/32), and a hard-surfaced runway on a 090/270 degree magnetic orientation (runway 9/27). On the day of the accident, runway 16 was in use. It has a displaced threshold of 500 feet, and is 6,000 feet long and 60 feet wide.

Wreckage and impact information

The NTSB IIC examined the airplane wreckage at the accident site on June 29, 2002. Four lateral gouge marks, perpendicular to the centerline of the runway surface, were the first impact marks located along the centerline of runway 16 at the Palmer Airport. The gouge marks began about 300 feet south of the runway's 4000 feet remaining sign.

The first gouge mark was 13 inches long, just east of the runway centerline. The second gouge mark was 12 inches long, and 12 feet, 5 inches south of the first mark. The third mark was 26 inches long, and 11 feet, 9 inches south. The last mark was 23 inches long, and 11 feet, 2 inches south of the third mark.

These

Aircraft

Registration
N435PR
Reported as
Denzer RAF 2000
Category
Gyroplane, amateur-built
Serial number
H2-00-11-455
Airframe hours
57
Engine
Subaru EJ-22, 130 horsepower, reciprocating
Damage
Substantial damage
Flight
Personal · Part 91
Registered owner
Raymond D. Denzer
Airworthiness certificate
Special, Experimental (Special)
Last inspection
Condition · January 7, 2002 · 57 hours before
Departed
PAAQ · Palmer, AK
Airport
PAAQ · Palmer Municipal Airport, runway 16, 6,000 × 60 ft, asphalt

Matched to the registry by N-number and the event date; the registry’s history has gaps, so older matches can be wrong. Compare the reported make and model.

Flight crew

As NTSB recorded them. NTSB leaves out names.

Role
Pilot
Age
57
Injuries
Fatal
Certificate
Private
Airplane ratings
Single-engine land
Medical
Class 3, Valid Medical--w/ waivers/lim
Last flight review
August 27, 2001
Seat
Left
Toxicology
Performed
Flight hours
204 total · 44 in this make and model · 92 as pilot in command

Weather

Conditions
Visual (VMC) · Day
Wind
Variable at 4 knots
Visibility
10 statute miles
Lowest ceiling
None
Temperature
59 °F, dew point 48 °F
Altimeter
29.54 inHg
Observed at
PAAQ

Docket · 18

The files NTSB released with the investigation on March 7, 2003, on NTSB’s docket system: statements, records, photos and specialists’ reports. 4.5 MB in all.

Witness StatementsItem 1 · .PDF · 207 KBMaps or Charts of Accident Area, Wreckage DiagramsItem 2 · .PDF · 416 KBWeather Reports and RecordsItem 3 · .PDF · 56 KBTranscript of Radio CommunicationsItem 4 · .PDF · 68 KBFAA Personnel StatementItem 5 · .PDF · 90 KBToxicological ReportItem 6 · .PDF · 64 KBMedical Records (Autopsy) InformationItem 7 · .PDF · 7 KBPhoto 1: View of runway 16, Palmer, AK., looking south. Note perpendicular gouge marks on runway surface. Wreckage point of rest is in the background.Item 8 · .PDF · 288 KBPhoto 2: View of runway surface looking south. A portion of gyroplane rudder is at right edge of photo along with additional scattered parts of the rudder. A portion of tailwheel is at left edge of photo.Item 9 · .PDF · 329 KBPhoto 3: View of wreckage point of rest with view of tailwheel in foreground.Item 10 · .PDF · 289 KBPhoto 4: Closer view of separated tailwheel assembly with shattered vertical stabilizer attached.Item 11 · .PDF · 349 KBPhoto 5: Closer view of impact area on runway surface, and wreckage point of rest.Item 12 · .PDF · 356 KBPhoto 6: View of aft end of gyroplane at point of rest, lying on left side.Item 13 · .PDF · 339 KBPhoto 7: View of wreckage point of rest, looking north along runway 16.Item 14 · .PDF · 313 KBPhoto 8: View of main rotor hub and blades, broken from the mast.Item 15 · .PDF · 357 KBPhoto 9: Closer view of rotor hub, blades, and mast.Item 16 · .PDF · 383 KBPhoto 10: View of rotor blades at point of rest.Item 17 · .PDF · 335 KBPhoto 11: View of aft end of gyroplane and engine propeller blades.Item 18 · .PDF · 269 KB

FAA reports on this event · 1

The FAA’s own accident and incident reports, matched to the aircraft by N-number and date.