Date: 201403
Local time of day: 0601-1200
Location: ZZZ.Airport, US
Light: Daylight
Aircraft: B747 Undifferentiated or Other Model
Operator: Air Carrier
Operating under: Part 121
Flight phase: Parked
Aircraft component: Exterior Pax/Crew Door
Reporter organization: Air Carrier
Reporter function: Technician
Reporter qualification: Maintenance Airframe; Maintenance Powerplant
Human factors: Communication Breakdown; Confusion
Anomaly: Aircraft Equipment Problem Critical
Detector: Person Maintenance
When detected: Other During Maintenance
Result: General Maintenance Action
Contributing factors: Chart Or Publication; Equipment / Tooling; Human Factors; Manuals; Procedure
Primary problem: Procedure

Narrative: Company Air Carrier's Escape Slide Safety Checklist may not provide adequate protections on Boeing 747-400 aircraft to prevent a slide deployment while a Main Entry Door (MED) Task is in progress. During a review of the Aircraft Maintenance Manual (AMM) 12-21-11; I noticed that the 'Warning' in AMM 12-21-11; Section 2; H; (1) informs the Mechanic to install a Safety pin into the door Emergency Power Reservoir (EPR) bottle. After the pin is installed; this AMM is for Girt Bar Servicing; Maintenance can be done. However; the second part of the Task asks the Mechanic to place the door Mode Selector Lever into the 'Armed' position (AMM 12-21-11; 2; H; (5); (d)) for cleaning and lubrication of the girt bar locks. There is a different 'Warning' informing the Mechanic to: 'turn the handle slowly to the necessary limit; if you turn the handle and open the door the Escape System will operate; this can cause injury or damage.' If the Escape System operates; the slide raft may deploy since the [slide] girt bar locks are in the floor fittings at this point of the task. AMM 25-69-03; 3 has the same two warnings; section has the same warnings and even a section on what to do if the slide raft pack opens (AMM 25-69-03; 2). No resolution at this time.

Callback: Reporter stated that mechanics are dealing with two different manuals when involving cabin Door slides; the Aircraft Maintenance Manual (AMM) and their General Maintenance Manual (GMM). The 'Warnings' are in the AMM; but limited in the GMM. He is not sure if the procedures also call out for the slide inflation bottle safety pin to be installed during the cleaning of the Girt Bar mechanism at the floor level. His Air Carrier said they were going to revise or include similar warnings in their GMM manual. But the problem is also in the type of safety pin installed in the door Emergency 'Open' Power Reservoir (EPR) bottle that has failed to prevent inadvertent openings of a cabin door while maintenance is being performed; resulting in a slide deployment. Reporter stated this is especially of concern during the Girt Bar lower mechanism cleaning procedures when Mechanics are directed per the AMM to place the door slide Mode Selector Lever into the slide 'Armed' position and than have to open the door slightly to access the Girt Bar and floor fittings. He has 32 years of aircraft maintenance experience.



Synopsis: An Aircraft Maintenance Technician (AMT) reports that a company Escape Slide Safety Checklist may not provide adequate protections for mechanics on their B747-400 aircraft when performing the cleaning and lubrication of the door slide Girt Bar and floor fittings.