I'm not an engineer at all, but from my experience in accident litigation, and working for 35 years with some of the best consulting engineers, this one won't take long to solve.
The spar failures occurred from either overload (G forces beyond their structural limits) or some form of weakening of the structures, such as happens with excessive corrosion. Of course, once one wing fails, the forces put upon the remaining wing can quickly overload what was a good structure. Another aspect that shouldn't adversely effect those of us operating as sport pilots was that this was a D model, not an LSA eligible airplane, and it was being flown by a pilot with a current medical, in the case that some form of pilot incapacitation caused a loss of control with resulted in overloads to the structure. A sad accident, but let's hope that is wasn't due to undetected corrosion. Jerry E. -----Original Message----- From: [email protected] [mailto:[email protected]]on Behalf Of ercoupe1 Sent: Saturday, December 27, 2008 10:29 AM To: [email protected] Subject: [ercoupe-tech] Sebring crash, NTSB preliminary report NTSB Identification: ERA09FA087 14 CFR Part 91: General Aviation Accident occurred Saturday, December 13, 2008 in Sebring, FL Aircraft: ERCOUPE 415-D, registration: N99154 Injuries: 2 Fatal. This is preliminary information, subject to change, and may contain errors. Any errors in this report will be corrected when the final report has been completed. On December 13, 2008 at 1206 eastern standard time, an Ercoupe 415- D, N99154, was destroyed during an in-flight breakup near Sebring, Florida. The certificated commercial pilot and the passenger were fatally injured. Visual meteorological conditions prevailed, and no flight plan was filed for the local flight, which departed Avon Park Executive Airport (AVO), Avon Park, Florida about 1115. The personal flight was conducted under the provisions of 14 Code of Federal Regulations Part 91. According to a friend of the accident pilot, who was also a certificated aircraft mechanic, he and the pilot flew together in the accident airplane immediately prior to the accident flight. The friend did not note any abnormalities with the performance of either the airplane or the pilot during their flight, and upon returning to AVO, the friend disembarked the airplane and the accident passenger boarded. Numerous witnesses observed the airplane flying in the local area around the time of the accident. One witness was outside talking with a neighbor when he observed the airplane flying overhead. The airplane was initially flying southwest, and made a "very slight dip and turned to the right. Then the airplane pulled up severely and started turning to the left." As the airplane continued upward and banked to the left, something "shiny" exited from the tail area of the airplane. The witness remarked to his neighbor, "What the heck is he dumping," and the airplane then began to break apart. The witness added that he did not hear any type of explosion and did not observe any smoke or fire. Another witness, who was also a certificated airline transport pilot, stated that while outside working on his house he observed the accident airplane flying overhead. He estimated that the airplane was flying at an altitude about 1,200 feet above ground level, and did not note anything abnormal about its flight path. About 45 minutes after first seeing the airplane, he heard an abnormal engine sound that diverted his attention again back to it. The witness stated that the engine sound was smooth, continuous, and sounded as if the engine was being "over-sped," as if the engine were at full power and the airplane was in a high speed dive. When he looked up, he saw the airplane pitching up and rolling into a steep left bank, and initially thought that the pilot was attempting to perform a "barrel-roll or a slow roll." From his position, he could see the bottom of the airplane, as well as both wings, as the airplane traveled north. He additionally noted that while the airplane was banking, both ailerons were "fluttering" at a high frequency. The bank angle increased to almost 90 degrees, when the left wing of the airplane "folded back" and separated from the fuselage. The airplane then pivoted about the lateral axis 90 degrees, and the right wing then separated from the fuselage along with a portion of the cabin. The wings "fluttered" or "twirled" to the ground, while the portion of the cabin continued forward and down to the ground. He recalled hearing three distinct "thuds" as the pieces of the airplane impacted the ground. The witness also reported that during the breakup, the airplane released what initially looked like "confetti," which he later determined to be painted chips of dope from the airplane's fabric covered wings. The weather conditions reported at Bartow Municipal Airport (BOW), Bartow, Florida, located about 24 nautical miles west of the accident site, at 1152, included winds from 020 degrees at 9 knots, gusting to 15 knots, 20 statute miles visibility, clear skies, a temperature of 16 degrees Celsius (C), a dewpoint of 6 degrees C, and an altimeter setting of 30.21 inches of mercury. The pilot held a commercial pilot certificate with ratings for airplane single engine land and sea, airplane multiengine land, and instrument airplane. He also held a flight instructor certificate with ratings for airplane single engine, airplane multiengine, and instrument airplane. His most recent FAA second class medical certificate was issued on June 2, 2008. Examination of the pilot's most recent logbook, which began on May 3, 2001, revealed that he had logged 7,126 total hours of flight experience, 12 hours of which were in the accident airplane make and model. According to records provided by the FAA, the accident airplane was manufactured in 1946. According to maintenance records, the airplane's most recent annual inspection was completed on May 9, 2008. At the time of the inspection, the airplane had accumulated 2,588 total hours of operation. The in-flight breakup occurred over a residential community built around a golf course. Portions of wreckage were found along a wreckage path that was 3,100 feet long, and oriented on a magnetic heading about 020 degrees. The first pieces of wreckage, found at the most southern end of the wreckage path, included both aft cabin windows. Paint chips, inspection panels, and various personal effects from inside the airplane were located further along the wreckage path, with the right wing being the next most substantial component located. The right wing was located about 2,000 feet from the aft cabin windows, along the wreckage path. The wing was lodged in the ground, oriented perpendicular to the terrain. The wing remained largely intact, and was separated from the fuselage at the wing root, just inboard of the leading edge fuel tank. The wing spar remained intact to a point about 1-foot inboard of the wing root, where it separated from the remainder of the airplane's structure. Ten of the right wing's 17 inspection port covers were dislodged, and located at various points along the wreckage path in an inverted or "popped" position. All of the displaced covers had, with one exception, come from the wing root, leading edge, and outboard edge, while the inspection covers from the center and trailing edge portions remained in place. The left wing was located about 900 feet beyond the left wing, along the wreckage path. The left wing spar was fractured at a similar location as the right wing spar. Several of the inspection port covers were dislodged, but did not display any discernable pattern as was observed on the right wing. The inboard portions of both wing spars were forwarded to the National Transportation Safety Board Materials Laboratory for further examination. The main portion of wreckage came to rest about 200 feet beyond the left wing, along the wreckage path. The nose, cabin, and aft portion of fuselage exhibited extensive crush damage, and its entirety was contained with an area about 10 by 10 feet. The cabin was severely compromised, and the seat pan, where both occupants were located, was found about 125 feet north of the main wreckage. The empennage, horizontal and vertical stabilizers remained largely intact, but separated from the remainder of the fuselage, and was co-located with the main wreckage. The propeller was lodged in a shallow impact crater, and remained attached to the engine at the propeller flange. Chordwise scratching and burnishing was present on both blades. Aileron and rudder control continuity was traced from the flight control surfaces to the control "mixing" bellcrank, normally located just aft of the main spar carrythrough. Separations of the aileron control push-pull tubes were noted at both wing roots, and the elevator push-pull tube was separated about 1-foot forward its bellcrank.
