Maintenance matters

Flying Safety, Sept, 2004

In the section of the job guide which describes the task being performed at the time of the mishap, there is a warning which states: "Ensure personnel and equipment are clear of movable surfaces anytime that hydraulic power is turned on to prevent injury to personnel or damage to equipment."

Although there were no obstructions at the beginning of the task, MP1 failed to recognize the possibility of the job guide falling toward the stabilizer as power was applied. The result was that team members failed to properly secure their equipment prior to hydraulic power being applied. What is your team communication like? Are your maintainers talking to each other to ensure they don't make the same kind of mistake?

Oil Thirsty Engine

While performing a routine postflight/preflight inspection, the crew chief noticed metal chips on the engine master chip detector (MCD). He also noticed the engine consumed eight half-pints of oil. A joint oil analysis program (JOAP) sample and MCD were sent to the non-destructive inspection (NDI) lab for analysis. The JOAP sample revealed no discrepancies. However, the jet scan analysis on the MCD revealed level three chips of M-50 (No. 1 bearing material). Additionally, during the intake inspection, the crew chief noticed a puddle of oil underneath the forward sump cover. The tech order troubleshooting procedures for high levels of M-50 requires an engine isolation run. Due to the discovery of oil in the intake, senior flight line maintenance personnel elected not to perform the isolation run. Instead, maintenance removed the engine and sent it to the engine back shop. After removing the forward sump cover, engine shop personnel discovered the No. 1 bearing retaining nut missing. In addition, the No. 1 bearing inner race had migrated forward. This caused the bearing to ride on the fan rotor shaft, which produced the level three M-50 chips found on the MCD.

A review of the engine maintenance records revealed that the last time the forward sump cover was removed from the engine was when the engine was removed for high engine total accumulated cycles. The engine overhaul was performed by a depot field team, and during the engine build-up, the engine technician failed to install the No. 1 bearing retainer nut. Additionally, the engine inspector failed to properly inspect the procedure. Both the technician and inspector signed the in-progress inspection (IPI) worksheet acknowledging that the work was completed. This incident occurred simply because tech data was not followed during engine build-up. Additionally, the engine inspector signed off the IPI worksheet without having physically inspected the procedure. Senior maintenance personnel stated that this engine would have seized if it had flown just one more flight. How close are you following tech data? Good work by the crew chief and senior leaders for making the right calls!