In a report to the NASA Aviation Safety Reporting System, a potential problem was revealed by the technician who submitted a report on a Boeing 737-400. NASA’s Linda J. Connell, director of the ASRS, sent this report to the FAA, NTSB, and other aviation organizations: "ASRS received reports from A&P mechanics concerning rags that were left wrapped around the [trim] jackscrew. A pilot report was written up earlier about problems, in flight, trimming the stabilizer to zero degrees. During a previous sliding-seal replacement job, the reporters covered the jackscrew with rags to protect it from drill shavings and debris. The A&P mechanics were unable to complete the sliding-seal installation because of other necessary sheetmetal repairs. No verbal handoff or job card write-up was done about removing the rags on the jackscrew. During the next shift, another maintenance crew replaced the sliding seal without entry through the jackscrew compartment as required. That crew was unaware of the rags and returned the aircraft to service.

In the narrative from the mechanic who submitted the report to ASRS, the submitter wrote: "My shift began with a tremendous workload to accomplish in a short amount of time, including two sliding seals on two different aircraft, both with late arrivals. I temporarily put rags on the jackscrew to protect myself and avoid possible damage to the jackscrew. At this time we found damage to the spar, and sheetmetal was called to evaluate it. Sheetmetal required engineering assistance. We installed the sliding seal temporarily."

After completing a sliding-seal installation on another aircraft and waiting for the first aircraft to be moved into the hangar, "we documented the work completed on the seal assembly."

The mechanics worked on another problem, then: "The next shift never showed up for a turnover. We did not document use of rags on the jackscrew because the rags could be seen easily when entering the tail compartment to finish the job. We have always entered the tail compartment to complete the installation of attaching hardware. We did not know it was possible to complete the installation of the sliding seal from outside the aircraft."

In a follow-up call from ASRS, the submitter stated that: "The job card for installation of the sliding seal indicated clearly that entry into the jackscrew compartment was necessary. The next shift technician did not enter the compartment, but replaced the seal from the exterior of the aircraft. It was believed the next shift technician would replace the seal from the interior of the jackscrew compartment and clean the area after the job was completed."

Mechanics are welcome to submit reports to NASA’s Aviation Safety Reporting System database.

To make a submission, go to http://asrs.arc.nasa.gov. While most of the reports are from pilots, there are a substantial number submitted by mechanics, and they are full of useful information