ANC07FA109

A corrosion-induced fatigue fracture of the airplane's left wing to fuselage attachment cap fitting, which resulted in a partial separation of the left wing, and an uncontrolled descent.

The float-equipped airplane was transporting sport-fishing clients returning to a lodge from a remote fishing site. The pilot contacted lodge personnel while en route, and estimated his arrival time in about 3 minutes. When the airplane failed to arrive, an aerial search discovered the wreckage about 10 miles from the lodge, along the anticipated flight route. The NTSB's investigation revealed evidence that the airplane's lower left wing to fuselage attachment cap fitting had failed in flight, which resulted in the airplane's uncontrolled descent. The deformation at the upper forward and aft wing attachment points suggested that the airplane's left wing, in part, had failed in flight, but did not completely separate from the airplane. A subsequent metallurgical examination revealed that the fractured wing to fuselage attachment cap fitting displayed evidence of fatigue cracking, which emanated from areas of corrosion pitting. A Safety Board metallurgist noted that the corrosion pitting was located in the interior portion of the pin/bolt hole, where a large bore pin/bolt resides when the wing is attached to the fuselage, which is not visible when the bolt/pin is installed. The metallurgist also noted that there was corrosion on the forward and aft faces of the fitting that would have been visible. Other than the corrosion pitting on the attachment cap fittings and pins/bolts, no metallurgical anomalies were discovered. On September 9, 2008, the FAA issued a special airworthiness information bulletin (SAIB CE-08-47) recommending a visual inspection for evidence of corrosion, cracking, and other damage on the spar fittings, attachment bolts and related structure, to preclude a structural in-flight failure of the wings.

HISTORY OF FLIGHT On September 30, 2007, at an estimated time of 1720 Alaska daylight time, a float-equipped Helio H-295 airplane, N295BA, collided with tree and tundra covered terrain, about 40 miles northeast of King Salmon, Alaska. The airplane sustained substantial damage. The airplane was owned and operated by Branham Adventures, Anchorage, Alaska, and was being operated as a visual flight rules 14 Code of Federal Regulations Part 91, other work use flight when the accident occurred. The certificated commercial pilot and the three passengers sustained fatal injuries. Visual meteorological conditions were reported in the area at the time of the accident, and company flight following procedures were in effect. The flight originated at a remote lake, and was en route to the Royal Wolf Lodge when the accident occurred. During an interview with the National Transportation Safety Board (NTSB) investigator-in-charge (IIC) on October 2, the owners of Royal Wolf Lodge reported that the accident airplane was being used to transport sport-fishing clients, and a lodge guide, to remote areas for fishing. They said that the accident occurred on the last flight of the day, as the airplane was returning to the lodge from Hammersly Lake, about 20 miles southeast of the lodge. The owners also noted that Royal Wolf Lodge and Branham Adventures were jointly owned businesses. About 1715, the accident pilot radioed lodge personnel that he was en route to the lodge, with an estimated arrival time of about 3 minutes. No further radio communications were received from the accident airplane. When the airplane failed to arrive by 1730, lodge personnel attempted to contact the accident airplane via radio. No emergency locator transmitter (ELT) signal was detected on the lodge's radio equipment, and about 1745, the lodge owner initiated an aerial search along the pilot's anticipated route. He discovered the wreckage about 10 miles from the lodge, along the anticipated flight route, in an area of flat, sparsely tree, tundra-covered terrain. A search and rescue team was assembled at the lodge consisting of lodge employees. Dark night conditions delayed the search and the discovery of the wreckage until about 2130. The search team confirmed that all of the airplane's occupants had sustained fatal injuries. PERSONNEL INFORMATION The pilot held a commercial pilot certificate with airplane single engine land, airplane single engine sea, instrument airplane, and glider ratings. He also held private pilot privileges with an airplane multiengine land rating. Additionally, he held a flight instructor certificate for gliders. His most recent second-class medical certificate was issued April 6, 2007, and contained the limitation that he must wear corrective lenses. In the Pilot/Operator Aircraft Accident Report (NTSB Form 6120.1) submitted by Branham Adventures, the pilot's total aeronautical experience was listed as 9,000 hours, with 3,000 hours in the accident airplane make and model. The report noted that in the preceding 90 and 30 days prior to the accident, the pilot accrued a total of 260 hours and 75 hours. No personal flight records were located for the pilot, and the aeronautical experience listed on page 3 of this report was obtained from a review of the Federal Aviation Administration's (FAA) airmen records on file in the Airman and Medical Records Center in Oklahoma City. On the pilot's application for medical certificate, dated April 6, 2007, he indicated that his total aeronautical experience consisted of 9,200 hours, of which 100 were logged during the previous 6 months. AIRCRAFT INFORMATION According to the Pilot/Operator Aircraft Accident Report (NTSB Form 6120.1) submitted by Branham Adventures, the airplane had a total time in service of approximately 8,733.5 flight hours. The last recorded inspection of the engine and airframe was an annual inspection, on May 24, 2007, about 246.6 hours before the accident. The engine was overhauled on May 31, 2005, by Aero Recip of Alaska, LLC., and at the time of the accident had about 1,172.9 hours since overhaul. Previous Accident History A review of the airplane's accident history revealed that on October 6, 2000, it was involved in a previous accident near Port Alsworth, Alaska, following a loss of engine power [ANC01LA003]. As a result of the loss of engine power, the airplane collided with trees during a subsequent forced landing, sustaining substantial damage to the fuselage, wings, and empennage. According to the owners of Branham Adventures, following the October 6 accident, the airplane was recovered from the accident site, and transported to their Anchorage maintenance facility for repairs. A damage assessment revealed that the airplane's wings were damaged beyond economical repair. On November 3, 2000, Branham Adventures purchased a replacement set of wings from an aircraft salvage dealer in Fairland, Oklahoma. An airframe logbook entry dated May 10, 2001, noted that when the replacement wings were installed, the wings had 3,032.6 flight hours. The replacement wings were installed 1,794.8 before the accident . During a telephone conversation with the NTSB IIC on August 27, 2008, the aircraft salvage business owner said that the set of wings that were sold to Branham Adventures were previously removed from N5460E, a 1965 Helio H-250. He said that he purchased the salvage rights of N5460E from an aviation insurance company following an accident on May 18, 1995, in Clarkson, New York [NYC95LA112]. The salvage dealer said that the wings were not damaged during the accident, and that no repairs were required before he sold the wings to Branham Adventures. The salvage dealer said that he closed his business in 2006, and no records were retained concerning the sale of the wings to Branham Adventures. METEOROLOGICAL INFORMATION The closest official weather observation station was King Salmon, 40 miles west-southwest of the accident site. On September 30, at 1736, an Aviation Routine Weather Report (METAR) was reporting, in part: Wind, 260 degrees at 19 knots with gusts to 27 knots; visibility, 8 statute miles; clouds and sky condition, 1,700 feet few, 2,400 feet scattered, 4,100 feet broken; temperature, 46 degrees F; dew point, 42 degrees F; altimeter, 29.34 inHg. During interviews with the NTSB IIC on October 1, pilots that landed at the lodge about 25 minutes before the accident airplane's proposed arrival, with similar flight routes, characterized the weather conditions as westerly winds at 5 to 10 knots; visibility, 10 statute miles; clouds and sky condition, 5,000 feet overcast. Both pilots' remarked that there were transient and localized rain showers along their flight routes. WRECKAGE AND IMPACT INFORMATION On October 1, about 1130, the NTSB IIC, along with three National Park Service rangers, inspected the accident airplane. All of the airplane's major components were located at the main wreckage site. Prior to ground impact, the airplane collided with trees about 15 feet tall. The initial crash path was marked by broken treetops on a magnetic heading of approximately 240 degrees. The subsequent descent angle to the ground was about 45 degrees. The airplane's initial impact point on the ground was discernible by an area of disturbed tundra, which contained the airplane's left (red) navigation light, and a clear strobe light lens. About 30 feet from the initial impact point was a crater, about 5 feet in diameter and 3 feet deep. The main portion of the airplane's fragmented wreckage was located about 45 feet beyond the initial ground impact. The engine and propeller assembly were discovered within the initial impact crater, with only the aft portion of the engine visible. The engine sustained extensive impact damage to the underside, and front portion of the engine. The exhaust tubes were extensively c