AMM 27-51 — Trailing Edge Flap Actuator Replacement
B737-800 flap actuator change. ALL THREE hydraulic sources must be isolated - the flight controls are redundantly driven.
It refers to equipment that does not exist and illustrates the elements 29 CFR 1910.147(c)(4)(ii) requires a procedure to contain. It is not a document to adopt. Under (c)(4)(i) the employer must develop and document energy control procedures specific to their own machines, and under (c)(6) must inspect them at least annually.
Other standards also apply to this work
- The operator’s approved maintenance programme and the AMM task govern. This example illustrates energy isolation only.
13 points, in sequence
Landing gear ground lock pins, all three gear. Prevents retraction. Fitted before work, removed LAST.
External power / GPU disconnect at the forward service panel.
APU master switch and APU fire switch. APU can start remotely and pressurise the pneumatic system.
System A engine-driven pump shutoff valve, engine 1 fire switch position.
System A electric motor-driven pump circuit breaker, P6-1. Pull and collar.
System A accumulator bleed. 3000 psi with nitrogen precharge - bleed to zero and confirm on the gauge.
System B engine-driven pump shutoff valve, engine 2 fire switch position.
System B electric motor-driven pump circuit breaker, P6-2. Pull and collar.
System B accumulator bleed. Independent of system A - both must be bled before flight control work.
Standby hydraulic pump circuit breaker. THIRD source on the same flight controls - often missed.
Trailing edge flap surface secured against movement. Residual pressure can drive the surface.
DO NOT OPERATE placards on the flap lever and hydraulic panel. Warning only - NOT an isolating device.
Battery switch and battery bus. Hot battery bus REMAINS LIVE for fire detection - cannot be fully isolated.
What your site must supply
This example is structurally complete and factually generic. The things below are the things only you can know — and they are exactly what makes a procedure yours.
- Your own asset and isolation-point tag numbers. The tags shown are illustrative and refer to equipment that does not exist.
- The actual location of every disconnect, valve and vent on your equipment.
- Measured stored-energy magnitudes and the dwell time required to dissipate them.
- Your verification method for each point, and who is authorised to perform it.
- Any additional energy sources present on your equipment and absent here.
Author this properly, once
Setyr holds procedures like this as living documents — bound to real isolation points, with lock registries, group lockout, person-in-charge custody and periodic review built in.