DeFuniak Springs, FL, USA
N9001N
GUTIERREZ PABLINO HUMMEL BIRD
Witnesses reported observing the airplane porpoising along its longitudinal axis during its climb after takeoff. About 300 feet above ground level, the airplane pitched up to a nose-high attitude and rolled to the right; it subsequently impacted the ground in a right-wing-low, nose-down attitude. Postaccident examination did not reveal any preimpact mechanical malfunctions or abnormalities that would have precluded normal operation. However, the weight of the airplane (not including fuel) plus the weight of the pilot exceeded the airplane's maximum gross takeoff weight and the center of gravity (CG) was aft of the most rearward limit. Although any fuel would have moved the CG forward of the most rearward limit, it also would have increased the airplane's takeoff weight. The pilot reported to his aviation medical examiner (AME) that the airplane was having "great" difficulty with longitudinal stability. He also noted that his weight gain caused the airplane to be "over gross," most likely causing the control problems. The AME advised the pilot to stop flying the airplane. Because the airplane was at or aft of the rear CG limit, it would have been very sensitive in pitch control and may even have been at or near a dynamically unstable flight regime in terms of pitch handling. Accordingly, the airplane would have required more nose-down trim adjustment. Additionally, because stall speeds increase as gross weight increases, the airplane would have stalled at a higher airspeed. Therefore, it is likely that, during the climb, the airplane stalled at a higher airspeed than the pilot would have expected due to its exceedence of the maximum gross weight and that it subsequently entered a spin. A review of the pilot's logbook indicated that he had accumulated only 4.4 flight hours in the 2 years preceding the accident flight with only 0.3 hour in the accident airplane. It is likely that the pilot's lack of experience in the airplane make and model contributed to his decision to take off with the airplane in an overweight condition and his inability to understand the seriousness of the situation. Although the postmortem toxicology testing was positive for three drugs used in the treatment of hypertension, none of the medications should have been impairing and were unlikely to have contributed to the accident.
HISTORY OF FLIGHTOn May 9, 2012, about 1110 central daylight time, an experimental, amateur-built, Gutierrez Hummel Bird airplane, N9001N, registered to, and operated by, the commercial pilot, impacted the ground in a nose-down attitude at the DeFuniak Springs Airport (54J), DeFuniak Springs, Florida. The pilot was fatally injured. Visual meteorological conditions prevailed. The personal flight was operated under the provisions of Title 14 Code of Federal Regulations Part 91, and no flight plan was filed. The flight was originating at the time of the accident. According to eyewitness reports, the pilot was observed performing maintenance to the airplane prior to the flight. One of the witnesses stated that he observed the pilot conduct a lengthy preflight before starting the engine by hand, followed by a ground engine run-up, and then taxi to runway 27. Witnesses observed the airplane accelerate, roll down the runway, rotate, and climb about 30 to 40 feet above the runway when the airplane started varying its altitude. They watched as the airplane porpoised a few times as it continued to climb. When it reached an estimated altitude of 300 feet above ground level (agl), it pitched nose high and rolled to the right. The airplane nosedived and collided with the ground in an approximate 80 degree nose-down attitude. The airplane came to rest on its main gear in the upright position facing 120-degrees from the departing runway. PERSONNEL INFORMATIONThe pilot, age 77, held a commercial pilot certificate with ratings for airplane single-engine and multi-engine land, and instrument airplane. He held a flight instructor certificate for airplane single-engine land. He was issued a third-class medical certificate on April 10, 2012, with the limitation of a special time limited; however, in a letter mailed to the airman on May 5, 2012, the Federal Aviation Administration (FAA) withdrew his medical certificate. A review of his pilot logbook revealed the most recent entry was dated March 15, 2012 and at that time he had 527.5 total hours of flight experience, of which 0.3 of those hours were in the accident airplane make and model. The most recent recorded flight review was dated August 22, 1997; however, in February and March of 2012, there were three entries with a flight instructor signature associated with them that listed a variety of training, including; "takeoff and landings, emergency procedures, failures" to list a few. AIRCRAFT INFORMATIONThe single-seat, low wing, all metal construction, fixed-gear airplane, serial number 001, was manufactured in 2012. It was powered by a 37-hp, 2-cylinder Hummel Engine, which consisted of 1/2 of a Volkswagen engine, and a Culver 2-bladed wooden propeller. Review of photographs of the airframe maintenance records revealed a conditional inspection was recorded by the accident pilot on January 9, 2010. The airplane was issued a special airworthiness certificate on January 10, 2010. The most recent airframe maintenance logbook entry was dated April 12, 2012, with a recorded tachometer time of 7.7 hours and stated, "Adjusted horizontal stabilizer = increase nose-down pitch." The entry was signed by the accident pilot. The most recent engine maintenance logbook entry was dated March 24, 2010, with a recorded tachometer time of 3.0 hours. METEOROLOGICAL INFORMATIONA review of the 1125 recorded data from the Bob Sikes Airport (CEW), Crestview, Florida, 19 miles west of the accident site included variable wind at 4 knots, visibility 10 miles, scattered clouds at 2,200 and 3,000 feet agl and a broken cloud layer at 11,000 feet agl; temperature 27 degrees C, dew point 20 degrees C, and altimeter 29.89inches of mercury. AIRPORT INFORMATIONThe single-seat, low wing, all metal construction, fixed-gear airplane, serial number 001, was manufactured in 2012. It was powered by a 37-hp, 2-cylinder Hummel Engine, which consisted of 1/2 of a Volkswagen engine, and a Culver 2-bladed wooden propeller. Review of photographs of the airframe maintenance records revealed a conditional inspection was recorded by the accident pilot on January 9, 2010. The airplane was issued a special airworthiness certificate on January 10, 2010. The most recent airframe maintenance logbook entry was dated April 12, 2012, with a recorded tachometer time of 7.7 hours and stated, "Adjusted horizontal stabilizer = increase nose-down pitch." The entry was signed by the accident pilot. The most recent engine maintenance logbook entry was dated March 24, 2010, with a recorded tachometer time of 3.0 hours. WRECKAGE AND IMPACT INFORMATIONThe airplane impacted the ground in a nose and right wing low attitude. It came to rest upright and the nose exhibited crush damage in the positive and aft direction which correlated to an eyewitness report of an almost 80 degrees nose down attitude. The airplane came to rest on a heading of 030 degrees. The initial impact location was identified by an approximately 2 feet deep crater, and one of the two wooden propeller blades was located within the crater. The other blade was located near the initial impact crater. The right wing outboard approximate one-half of the leading edge exhibited crush damage which was more pronounced at the wing tip. ADDITIONAL INFORMATIONAccording to fuel records provided by the airport, the most recent fuel purchase by the pilot was for 1.94 gallons of fuel on April 16, 2012. A review of the pilot's FAA medical records showed that on May 5, 2012, a letter was issued to the pilot that withdrew his medicate certificate issued on April 10, 2012; due to a recent change in the medication the pilot was consuming for his medical condition. The certified letter was delivered to the pilot's residence on May 10, 2012. According to information provided by the FAA Office of Aerospace Medicine, a letter from the Aviation Medical Examiner (AME) reported that during the most recent medical exam the pilot told the AME that "…he was having great difficulty with longitudinal stability, and was unable to complete even one pattern after multiple attempts. More than one of these attempted test flights ended with forced landings, and damage to the aircraft such that it had to be carried back to his hangar for repair. He noted his weight gain caused him to be 'over gross' most likely causing his control problem." The AME further reported that he had "advised the pilot, as did other friends, to stop trying to fly this plane and simply get a larger aircraft capable of carrying him." According to documentation located with the airplane maintenance records, a center of gravity calculations form was located. The form, dated June 2, 2011, indicated that the empty weight of the aircraft was 333 pounds, and that weight did not include the weight of the pilot or the fuel. The form also indicated that the center of gravity (CG) limits were 8.25 – 11.25 inches rear of datum and a maximum gross weight of 530 pounds. When calculating the weight, utilizing the pilot's most recent medical information and 2 gallons of fuel, the takeoff weight was 561.2 pounds with a CG of 11.14 inches rear of datum. When calculating the weight, as above, except with full fuel the takeoff weight was 588 pounds and a CG of 10.216 inches rear of datum. Pilot's Handbook of Aeronautical Knowledge (FAA-H-8083-25A) Chapter 4, "Aerodynamics of Flight," states in part "Generally, an aircraft becomes less controllable, especially at slow flight speeds, as the CG is moved further aft. An aircraft which cleanly recovers from a prolonged spin with the CG at one position may fail completely to respond to normal recovery attempts when the CG is moved aft by one or two inches…" Chapter 8, "Weight and Balance," states in part "Compliance with the weight and balance limits of any airplane is critical to flight safety. Operating an airplane above the maximum weight limitation compromises the structural integrity of the airplane and adversely affects its performance…an overloaded airplane may not be able to leave the ground, or if it does become airborne, it may exhibit unexpected and unusually poor flight characteristics…excessive weight reduces the flight performance of an airplane in almost every respect. The most important performance deficiencies of the overloaded airplane are…higher stalling speed." The chapter goes on to state, in reference to CG "…if the CG is displaced too far aft on the longitudinal axis, a tail-heavy condition will result. It is possible that an unfavorable location of the CG could produce such an unstable condition that the pilot could not control the airplane…" MEDICAL AND PATHOLOGICAL INFORMATIONThe Florida State Medical Examiner's Office, Pensacola, Florida conducted a postmortem examination of the pilot. The cause of death was "blunt impact to the head and neck." The FAA Civil Aeromedical Institute (CAMI) conducted toxicology testing on specimens from the pilot. The tests were negative for carbon monoxide, cyanide, and ethanol. The drug test was positive for Norverapamil, Verapamil, Losartan, in urine and blood, which are used in the treatment of high blood pressure, angina, and hypertension, all of which had been reported by the pilot.
The pilot's failure to maintain airplane control due to the airplane’s exceedence of its maximum gross weight and center of gravity’s most rearward limit and his lack of familiarity with the airplane make and model, which resulted in an aerodynamic stall and subsequent spin. Contributing to the accident was the pilot's decision to knowingly operate the airplane over the maximum allowable gross weight with reduced longitudinal stability.
Source: NTSB Aviation Accident Database
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