Aviation Accident Summaries

Aviation Accident Summary WPR09LA202

El Dorado HIlls, CA, USA

Aircraft #1

N209TP

ALEXANDER THOMAS P SPORTSMAN GS-2

Analysis

Witnesses monitoring the accident flight's departure airport common traffic advisory frequency reported that they heard a mayday radio transmission stating that "I've lost elevator control" and "I'm going down in some trees." Witnesses adjacent to the accident site reported hearing a loud whining noise followed by the sound of something impacting trees. One witness stated that the airplane was at a low altitude in an upright attitude when it struck trees. The airplane subsequently impacted terrain and came to rest near a residential structure where a post-crash fire consumed most of the fuselage. Post-accident examination of the wreckage revealed that the elevator torque tube was disconnected from the forward rod end bearing. The forward rod end bearing remained attached to the elevator bell crank assembly. No damage was observed on the forward torque tube rod end threads or forward rod end bearing threads. The forward torque tube rod end jam nut was observed threaded about one-half inch from the threaded rod end. The aft torque tube jam nut and torque tube rod end was observed against the aft rod end bearing. The aft torque tube rod end was slightly bent and did not allow movement. No evidence of "torque seal" was observed on the forward or aft jam nuts, rod end bearings, or torque tube assembly. No additional mechanical anomalies were noted with the recovered airframe.

Factual Information

HISTORY OF FLIGHT On April 17, 2009, about 1710 Pacific daylight time, an amateur built Alexander Sportsman GS-2, experimental airplane, N209TP, was destroyed when it impacted trees and terrain during a forced landing near El Dorado Hills, California. The airplane was registered to and operated by the pilot under the provisions of Title 14 Code of Federal Regulations Part 91. The private pilot, sole occupant of the airplane, was killed. Visual meteorological conditions prevailed and no flight plan was filed for the personal flight. The local flight originated from the Rancho Murieta Airport, Rancho Murieta, California, about 1618. A witness reported that while taxiing his airplane at RIU and monitoring the common traffic advisory frequency (CTAF) of 122.8 megahertz, he heard a radio transmission stating, "MAYDAY MAYDAY, I'm going down into the brush.... I've lost elevator control." The witness stated that he continued to monitor the frequency, but did not hear any further radio calls. A second witness, who was flying near Placerville, California, reported that while monitoring 122.8 megahertz, he heard someone transmit "Mayday! Mayday! Mayday!, (unintelligible call sign numbers) No elevator no elevator, I'm going down, I'm going down, no elevator, I'm going down, I'm going down in some trees!" A witness located adjacent to the accident site reported that while in their driveway, he noticed an airplane flying lower than usual and did not make any unusual sounds. The witness stated that the airplane appeared to be flying upright as it hit trees near his position. He added that while he "ran the other way for safety," he heard the airplane impact the ground. Another witness located near the accident site reported hearing a loud whining noise followed by the sound of something impacting trees. Upon looking outside their window, they observed an airplane in their neighbor's yard, on fire. Multiple residents adjacent to the accident site called 911 and attempted to contain the fire until emergency responders arrived. PERSONNEL INFORMATION The pilot, age 60, held a private pilot certificate with airplane single-engine land and airplane single-engine sea ratings. A third-class airman medical certificate issued February 22, 2008, with the limitations stated "must wear corrective lenses." The pilot's logbook was located within the wreckage and sustained fire damage. Review of the logbook revealed that as of the pilot's most recent logbook entry, dated April 11, 2009, he had accumulated 162.6 hours of flight time, of which 3.6 hours were in the accident make/model airplane and 2.1 hours within the previous 90 days. A family member of the pilot reported that he had accumulated about six or seven hours total flight time in the accident airplane. AIRCRAFT INFORMATION The two-seat, high-wing, fixed-gear airplane, serial number (S/N) 7297, was built in 2009 and subsequently issued an experimental airworthiness certificate on March 27, 2009. It was powered by a Lycoming IO-390-EXP, and equipped with a Hartzell Propeller model HC-C2YR-1BFP. The logbooks for the airplane were not located during the investigation. A family member of the pilot reported that the accident flight was about the fifth or sixth flight since the airplane was built and had about six or seven hours total flight time. The airplane was built by the pilot under the two weeks to taxi program at Glasair Aviation, Arlington, Washington. The pilot completed the program on February 20, 2009. The airplane was partially disassembled and transported via ground transport to the pilot's designated airport and subsequently reassembled. A Glasair Aviation representative reported that the pilot called their technical support line prior to his first flight in the accident airplane and inquired about engine break-in, rigging of the elevator, fuel calibration, and first flight advice. The representative stated that he advised the pilot that the elevator travel was 23 degrees up and 20-degrees down, plus or minus one degree. He further stated that the pilot informed him that the "jig that he built while here in the program and the travel wasn't exactly those figures" and would "check the travel again to make sure it was within the tolerance and make the changes if necessary." Review of the Two Weeks to Taxi Program Outline provided by Glasair Aviation revealed that page 11, section X, "Getting Your Sportsman Airworthy" states in part "the Two Weeks to Taxi program moves at a rapid pace and, although your aircraft may look and feel like it is airworthy when it leaves our facility, it is not. Yes we assist you in getting all the way to taxi in a very short time, but we want to make sure you fully understand that your aircraft is not 'airworthy' when it leaves our facility." The section further states "one of the most critical set of tasks to be completed after you leave the Two Weeks to Taxi program are the final operational checks and safety inspections of all assemblies, rigging, flight controls, and aircraft systems….As a part of this inspection process, you and the A&P must independently check and double check each item listed in Section X of your Assembly Manual under ‘Systems Checkout’ and ‘Fastener Inspection and Safetying’.” The Sportsman Assembly Manual, Section X: Final Assembly, page 352, heading “Systems Check-Out”, states in part “This sub-section describes an inspection of all the aircraft systems to make sure they’re working properly before taxi and flight testing.” Page 353, heading “Step 187: Inspect the Control System”, states in part “Make a final check to verify that all flight control surfaces have the prescribed travel…. Adjust the control stops, as necessary…. Insert a piece of wire into the inspection hold in each rod end bearing in the control system to verify that there are enough threads engaged….Double check that all jam nuts are properly torqued (with a wrench) and witness-painted.” Section X, Final Assembly, page 359, heading “Fastener Inspection and Safetying, states “Before flying your Sportsman, it’s imperative that you perform a systematic inspection of the entire airframe, with an emphasis on checking that each fastener is properly installed, tightened and safetied as necessary. Item E states in part “non-self-locking nuts that cannot be cotter-pinned to prevent rotation, such as the jam nuts that lock rod end bearings on control pushrods, should be checked for tightness. These nuts, we recommend applying witness paint across the interface of the nut with the part it’s being tightened as an inspection aid to detect rotation of the parts. Such rotation breaks the paint seal, indicating the need for corrective action. For witness paint, use a small dab of brightly colored fingernail polish or a product called “Torque Seal” made specifically for this application.” Page 364, heading “Step 203: Inspect the Elevator Control System”, states in part “Pushrod rod end jam nuts (witness paint)”. METEOROLOGICAL INFORMATION A review of recorded data from the Sacramento Executive Airport's automated surface observation station, located 25 miles southwest of the accident site revealed at 1753 conditions were wind from 230 degrees at 9 knots, visibility 10 statute miles, clear sky, temperature 24 degrees Celsius, dew point 9 degrees Celsius, and an altimeter setting of 30.09 inches of Mercury. WRECKAGE AND IMPACT INFORMATION Examination of the accident site by a Federal Aviation Administration (FAA) inspector revealed that the airplane struck the tops of 40 to 50-foot tall trees and subsequently impacted the ground about 300 feet from the first identified point of contact with trees. Multiple topped trees and down tree limbs were observed within the wreckage debris path. The airplane came to rest adjacent to a residential structure against a retaining wall and was mostly consumed by fire. All major structural components of the airplane were observed at the accident site. The left and right wings were separated from the fuselage. The left and right flaps and ailerons remained attached to their respective mounts. Examination of the recovered airframe revealed that the elevator torque tube was disconnected from the forward rod end bearing. The forward rod end bearing remained attached to the elevator bell crank assembly. The forward torque tube rod end jam nut was observed threaded about one-half inch from the threaded rod end. Gray colored paint was observed between the jam nut and torque tube. No paint was observed from the jam out to the end of the rod end. No damage was noted to the forward torque tube rod end threads or forward rod end bearing threads. The aft torque tube jam nut and torque tube rod end was observed against the aft rod end bearing. The aft torque tube rod end was slightly bent and did not allow movement. The aft elevator rod end bearing remained attached to the elevator control horn. No evidence of "torque seal" was observed on the forward or aft jam nuts, rod end bearings, or torque tube assembly. The elevator control cables remained attached to the elevator bell crank and continuity was established to the cockpit control column area. Control continuity was established from the left and right aileron to the wing root. All separations within flight control cable system exhibited "broom straw" and overload signatures or were cut by wreckage recovery personnel to facilitate wreckage transport. The elevator trim motor was removed and functioned normally from stop to stop when power was applied using a 9-volt battery. The position of the elevator trim was not determined. No additional mechanical anomalies were noted with the airframe. MEDICAL AND PATHOLOGICAL The El Dorado County Coroner conducted an autopsy on the pilot on April 21, 2009. The medical examiner determined that the cause of death was “massive blunt force trauma.” The FAA's Civil Aeromedical Institute (CAMI) in Oklahoma City, Oklahoma, performed toxicology tests on the pilot. According to CAMI's report, volatiles and drugs were tested, and had negative results.

Probable Cause and Findings

The in-flight separation of the elevator control torque tube rod end bearing from the elevator torque tube as a result of incorrectly tightened rod end bearing lock nuts.

 

Source: NTSB Aviation Accident Database

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