Short Wing Piper Club
According to Yavapai County sheriff deputies, the pilot made an unplanned stopover at the Bagdad airport because one of his passengers was airsick. About 30 minutes later they took off on runway 05. The aircraft began a right crosswind turn when it abruptly rolled and pitched downward. It maintained a nose down attitude until it collided with terrain.
The pilot received his private pilot certificate on February 18, 1997. His flight test and preceding training had been conducted in the accident aircraft.
According to the original aircraft and engine logbooks, the engine had been derated from an O-320-B2B 160 hp to an engine rated at 150 hp at 2,700 rpm. The work had been accomplished during a top overhaul and was performed in accordance to Lycoming service letter L126 on June 12, 1964. The serial number was the same as the number on the engine that had been installed at the time of manufacture. Based on the aircraft time at its last annual and the pilot's estimated flight time, the Safety Board estimated that the total airframe and engine time since new was 1,802 hours at the time of the accident.
The aircraft fuselage, wings, ailerons and flaps had been metalized on November 9, 1966, in accordance with STC SA-1-327, 325 and 282. At the time, a new empty weight was computed to be 1,175 pounds, and a new empty center of gravity moment was computed to be 11.27 pound/inches. The last recorded static system and altimeter checks found were dated August 16, 1994.
According to the insurance adjuster, the aircraft propeller had been repitched at Aviation Enterprises in Gilbert, Arizona, during its last annual inspection. The propeller hub bore a single stamp that stated that the propeller pitch was 60 degrees.
According to the propeller manufacturer, the diameter of the turning propeller ranges from 48 to 66 inches, with 60 inches being typical for a cruise pitch and 58 inches for a climb pitch. A 1-inch decrease in diameter equals an increase of 25 rpm.
The operator of the propeller shop told the adjuster that the pilot/owner had brought the propeller in to be repitched to improve climb performance under higher density altitude conditions. The work was accomplished by placing the propeller in a vise and using a bar positioned 18 inches from the hub to change the blade angle.
The propeller manufacturer stated that to repitch a propeller, the blades must be measured at six specified stations to ensure they match the angles in Sensenich propeller repair manual. It is also important that a blade angle template be used for angle measurements. If a template is not used, the resultant pitch angle will be higher than desired.
The aircraft was last refueled on March 18, 1997, with 18.4 gallons of 100 octane low lead aviation gasoline at the Laughlin/Bullhead International Airport in Bullhead City, Arizona.
The current aircraft and engine logbooks were not located.
Based on the reported temperature of 72 degrees and altimeter setting of 30.40 inHg, the Safety Board computed the density altitude at the Bagdad airport to be 6,572 feet.
The NOAA Airport/Facility Directory states under airport remarks that there are unusual air currents in the vicinity of the airport. Runway 05-23 exhibited a variable gradient. The terrain at the departure end of runway 05 drops and then rises.
WRECKAGE AND IMPACT INFORMATION
The crash site was located at 34 degrees 35.75 minutes north latitude, and 113 degrees 10.21 minutes west longitude. The site was about several hundred feet below and about 0.25 miles beyond the departure end of the runway. The aircraft impacted on a rising 20-degree slope in an area of sparse desert vegetation.
The aircraft came to rest on a magnetic heading of 340 degrees while in a near vertical, nose down attitude. There were no indications that the aircraft slid or rebounded after impact. All flight control surfaces remained attached to the aircraft and control continuity was established. Remaining debris from the aircraft was located within the immediate vicinity of the impact.
The left and right fuel caps separated and were found on the ground 18 and 25 feet, respectively, ahead of the wings. The fuel selector valve was found positioned between the "left" and "off" detents.
Blown air was introduced into the ports and they were found to be unrestricted. The valve was then
rotated by hand and did not exhibit any binding or sticking.
The two-bladed, fixed pitch, metal propeller remained attached at the propeller flange. The first blade was bent aft along the engine cowling. The blade exhibited slight leading edge damage and discoloration associated with thermal exposure. The second blade was missing from midspan outboard. The remainder of the blade exhibited evidence of discoloration and molten disfiguration associated with thermal exposure. Preimpact blade angles could not be determined.
The engine was found still attached to the airframe engine mounts and exhibited evidence of both thermal and impact damage. The vacuum pump and rocker box covers were removed. The crankshaft was then hand rotated through the vacuum pump drive pad. The crankshaft was moved in both directions and drive train continuity was established. Thumb compression and proper sequence were observed on cylinders No. 3 and 4. There was visible crushing to the pushrods to the No. 1 and 2 cylinders, and the valves did not fully seat during rotation. Once the pushrod tensioner and rocker pinch were removed, thumb compression was obtained on those cylinders as well. All four cylinders and pistons were bore scoped with no evidence of internal damage noted.
The spark plugs were in place with the leads attached. All eight plugs were removed and visually examined. The examination revealed that all the plug's electrodes were undamaged, and except for the plugs from the No. 4 cylinder, displayed coloration and wear consistent to normal operation according to the Champion Spark Plug Check-A-Plug chart. The No. 4 spark plugs electrodes were soaked with oil.
The left magneto remained attached to its mount and exhibited evidence of thermal distress. The impulse coupler was heard snapping during hand rotation of the crankshaft. The magneto did not produce a spark and the engine timing was not determined; however, the drive remained intact and was saftied.
The right magneto also remained attached to its mount and exhibited evidence of thermal distress. The magneto did not produce a spark; however, the drive remained intact and was saftied.
The carburetor was fractured with a portion still attached to the engine mounting surface. The throttle plate was intact and a portion of the control cable remained attached to the arm. Both the carburetor and airbox exhibited evidence of thermal distress. The airbox heat valve was in the cold position. The air filter element had been consumed by fire; however, the front and rear screens were intact and remained in their respective positions. The carburetor bowl was separated and the float assemble exhibited evidence of thermal distress. The airframe fuel strainer/filter displayed both impact and thermal damage.
The exhaust system displayed impact and thermal distress but remained attached at each cylinder. The muffler was removed and transectioned to expose the internal passages. No evidence of obstructions were found.
MEDICAL AND PATHOLOGICAL INFORMATION
An autopsy was conducted on March 20, 1997, by the Yavapai County Medical Examiner's Office, with specimens retained for toxicological examination. The toxicological test results were negative for alcohol and all screened drug substances except chlorpheniramine, an antihistamine, and phenylpropanolamine, a decongestant.
A witness reported that smoke and a small fire were observed almost immediately after impact, and that it took approximately 2 or 3 minutes until the aircraft was fully engulfed. She also stated that wispy black smoke rose from the fire in an undisturbed, vertical column.
The final NTSB cause of this accident has not yet been determined.