Class C mishap summary - Crossfeed

Mech, Fall, 2003 by Gary Dennis

From May 23, 2003 to Aug. 21, 2003, the Navy had 26 Class C's that involved 28 aircraft. The damage total was $1,297,744.

* An FA-18E was scheduled for a loads test flight. The external fuel tanks on wing stations 4 and 8 were full for this mission. When the flight was done, and, as the plane prepared to return to base, the pilot started to transfer fuel from the external tank to the internal tanks. The airfield was nearby, so all the fuel did not transfer before landing. The aircraft was not refueled after shutdown.

Civilian maintainers had to remove the external fuel tanks to prepare for a modification. The contract team leader knew the aircraft had not been refueled. The external tank on station 8 was about one-quarter full, and a team of six maintainers prepared to download that tank. Two people were on each end, and the plan was to lower it onto the ground-handling lift trailer (GHLT). The maintenance team leader supervised the procedure, and a contractor quality-assurance safety observer prepared to release the tank.

The maintainers on the tank linked arms to support the external fuel tank to lower it approximately six inches to the GHLT, which was extended to its maximum height. As the external fuel tank was released, it fell onto the GHLT.

The maintenance team failed to follow proper procedures outlined in the loading manual, which required them to open the filler cap and to visually check the fuel level. They chose to do a tap test.

This incident damaged the external fuel tank and the GHLT and cost $32,000.

* A P-3C crew was doing multiple approaches to an outlying field. During the third approach and immediately after selecting landing flaps at 300 feet AGL, the mission commander heard a loud bang, and the aircraft's right side began to vibrate. The mission commander took control of the aircraft and went around. After visually checking the No. 3 and No. 4 engines, the observer reported to the flight station that something looked different on the No. 3 propeller, but he wasn't sure what it was. The engine instruments were normal, so, after reaching pattern altitude, the flight engineer went to the nav-com to check out the problem. He saw that the No. 3 nacelle was shaking abnormally, and a gap appeared in the No. 3 propeller's are.

The flight engineer went back to the flight station and saw the No. 3 propeller rpm was fluctuating from 101 to 102 percent. After discussing possible malfunctions and procedural options, the mission commander decided to leave the prop and engine running and to land immediately. He briefed the NATOPS emergency-landing procedures, including steps to follow in case he had to shut down the bad engine on approach or landing.

Aircraft handling was normal throughout the approach and landing, but it changed on the landing ground roll. At about 80 kts, while smoothly reversing with engines No. 1, 2 and 4, the No. 3 engine and nacelle violently began to shake and affected aircraft controllability on the runway. The mission commander called for the No. 3 E-handle and secured the engine. The shaking immediately ceased, and the aircraft taxied to parking without incident.

The propeller EI noted that a visual inspection had revealed an intact anodized coating on the blade shank, but no evidence of foam was found on the blade shank. This condition indicated inadequate surface cleaning or preparation before the foam fairing was poured. Six years had passed since the last depot overhaul, so the reasons for the inadequate maintenance could not be determined. Depot reps stated this type of failure still occurs once every two years. They surmised that an error during the formation process could have weakened the blade-fairing and led to its inevitable failure. When it failed and separated from the No. 3 propeller, centrifugal force caused it to hit and to damage the No. 4 propeller and nacelle. This incident cost $139,583.

Senior Chief Dennis is a maintenance analyst at the Naval Safety Center, and he's the new editorial coordinator for Crossfeed.