DFW08LA223

The engine of the agricultural airplane lost power while it was maneuvering at low altitude. The airplane impacted thick vegetation and terrain, causing substantial damage to the right wing, nose and tail. A subsequent teardown examination of the engine showed little evidence that the engine was operating at the time of impact, but the ingestion of vegetation into the combustor and the torsional failure of the torsion shaft suggests that there was some rotation of the engine at the time of impact. The engine examination also revealed that several turbine rotors had damage and missing blade material due to short term operation of the engine at an over temperature condition. There was evidence that the rotors had been operating for several hours after the over temperature event that caused the stress rupture of the blades. Further, the examination showed that the first stage turbine rotor and the prop pitch control cam did not conform to Honeywell specifications and were not authorized replacement parts, and a previous weld repair on the engine combustor plenum did not conform to standard practices for weld repairs on aerospace parts.

On September 1, 2008, approximately 1500 central daylight time (CDT), a Rockwell International S-2R, N8472V, registered to Farm & Ranch Aerial Service Inc., and operated by Rusty’s Flying Service as a 14 Code of Federal Regulations Part 137 agricultural flight, crashed while maneuvering at low altitude. Visual meteorological conditions prevailed and flight plan had not been filed. The airplane was substantially damaged by the impact forces. The commercial pilot, who was the only occupant, was not injured. The airplane had departed the Glasscock Field Airport (4TS8) D’Hanis, Texas. The pilot reported he was half way through his third pass over a 200 acre cotton field and had 80 gallons of chemical and 180 gallons of fuel on board when the engine surged twice and then completely failed. The pilot was able to clear the bigger oak trees on the edge of the field and he stalled the airplane into a thick patch of brush. The Federal Aviation Administration (FAA) inspector that responded to the accident scene reported that the airplane appeared to have stalled tail first into thick vegetation, impacted terrain and came to rest upright. The right wing, nose and tail were crushed from the impact. One of the three blades on the propeller appeared to be undamaged. A second blade had a single bend and the third blade had a S- type bend. The wreckage was removed from the accident scene and transported to the facilities of Air Salvage of Dallas (ASOD), near Lancaster, Texas. On September 19, 2008 the Board investigator-in-charge examined the wreckage at ASOD and the engine was removed from the airplane and shipped to the Honeywell Product Integrity Investigation Laboratory in Phoenix, Arizona. On November 18, 2008 a teardown and examination of the engine was conducted at that facility under the oversight of an FAA inspector. The examination shows evidence of over temperature damage and missing material from turbine rotor blades. A metallurgical examination shows that the first stage turbine rotor and the prop pitch control cam do not conform to Honeywell specifications and are not authorized replacement parts. The configuration of the control system components on the engine do not meet the type certificate specifications and a previous weld repair on the engine combustor plenum does not conform to standard practices for weld repairs on aerospace parts. Airplane maintenance logbooks could not be located and were not available for inspection. The Hobbs meter reading at the accident site was 874.4. A few selected pages of maintenance records for the engine were located that covered the period from June 20, 2004 at 3369.5 engine time since overhaul (TSOH) until the last entry at 4763.4 TSOH on June 24, 2008. A maintenance record entry by a certified repair station on June 24, 2008, shows that a hot section inspection was performed; the engine was returned to service and reinstalled on N8472V at a Hobbs meter reading of 442.0.