20030417007029A

(-23) Aircraft lost power after takeoff. Engine went to uncommanded 70% power. Pilot dumped load, made emergency landing in cultivated field. Resulted in substantial damage to aircraft. No injuries to the pilot. Accident site was photographed by the owner before the aircraft was returned to the hangar. Visual inspection of the engine revealed that the primary fuel transfer tube, part number (p/n) 3011155 located between the number 5 and 6 fuel manifold adapter assemblies was not in its proper position. Visual inspection with a mirror showed that the "o" ring was protruding outside of the adapter on the lower side. Fuel leakage at this tube was confirmed by running the engine in the "as found" condition and observing a severe leak while the engine would not develop power above 72%ng. When the tube was re-positioned, the leak was not observed and the engine developed full power. These engine runs were observed by qualified mechanics, pilots and FAA personnel. Inspection of the entire fuel manifold installation showed that the transfer tube lock plates (p/n 3011158) at nozzle's 4 and 8 were slightly distorted. The secondary transfer tube between the number 4 and 5 adapter was not seated properly. At this position, the lock plate was resting on the shoulder of the tube rather than in the groove. Additionally it was noted that the igniters were safetied to their adjacent lock plates. A review of the maintenance records for the aircraft showed that the nozzles had been installed and functioning properly since 12/20/2002 and had accumulated 110.7 hours in service since that time. The engine had received a 100 hour visual inspection on 04/08/2003 which included an engine compartment cleaing, engine run-up and post run-up inspection for leaks. No leaks noted. No abnormal conditions were observed. At the time of the accident the aircraft had accumulated 3.9 hours since this 100 hour inspection. Follow up inspection with the repair station that performed the last fuel nozzle removal and reinstallation on 12/20/2002 showed that their stock of serviceable lock plates contained numerous distorted plates. The worse case was used to demonstrate that it could still be installed correctly and it would adequately retain the transfer tubes. However, the lock plates did not contact 100% of the transfer tube shoulder and they did not nest properly and fully in the transfer tube groove. Review of pratt & whitney overhaul data did not indicate any inspection criteria to be used when inspecting the lock plates for serviceability. Operating history of this engine indicates that this is an isolated occurrence. To preclude a recurrence of this condition it is recommended that: the engine manufacturer establish inspection criteria for the lock plates with particular emphasis on distortion of the lock plate flanges. Criteria to be used during overhaul or any time plates are removed and re-installed. Add a caution note to the locking plate removal procedure located in p&wc maintenance 3021242, chapter 73-10-05, page 202, item b, (3), alerting maintenance personnel not to pry the plates loose causing them to bend and become distorted.