Part-66 Module 7: maintenance practices checklist

Module 7 is the most practical B1 paper: 80 multiple-choice questions in 100 minutes, plus two essay questions that AeroPass does not mark. It rewards knowing what a careful technician actually does.

Safety and workshop practice

Use CO₂ on electrical fires and dry powder or sand on metal fires, never water. Isolate electrical supplies before helping a shocked person. Fit landing gear ground locks before working in wheel wells and treat propellers as live. Tool control (shadow boards, counts before and after work) prevents tools being left in aircraft; an aircraft is not released while a tool is missing. Torque wrenches and test equipment must be calibrated traceably; if a tool is found out of calibration, the work done with it must be assessed.

Measuring and tools

Metric micrometer: sleeve plus thimble in hundredths of a millimetre. Vernier: main scale plus coincident vernier division × resolution. Dial indicators measure run-out; feeler gauges measure gaps. Ammeters go in series, voltmeters in parallel, ohmmeters only on dead circuits. A megger tests insulation; a milliohmmeter tests bonding. Larger drills need lower speeds; general drills have a 118° point; reamers only turn clockwise.

Drawings and fits

Hidden detail uses dashed lines, centre lines use chain lines, hatching shows a section. Title blocks hold number, scale and revision. ATA chapters: 05 time limits, 12 servicing, 24 electrical power, 29 hydraulics, 32 landing gear. Clearance, transition and interference fits: maximum clearance = largest hole − smallest shaft.

EWIS, riveting and lines

Strip wire without nicking strands, crimp with the specified tool, use ring terminals, add drip and service loops, and never reset a tripped breaker repeatedly without finding the cause. In riveting, use Clecos, deburr holes, check heads with a rivet gauge and replace elongated-hole rivets with the next size up. Install O-rings lubricated and untwisted, with back-up rings on the side away from pressure.

Weight and balance

Moment = weight × arm; CG = total moment / total weight. % MAC = (CG − LEMAC) / MAC × 100. Weigh the aircraft level, indoors, in the configuration the manual specifies, and subtract tare.

Handling, inspection and abnormal events

Bond the fuel vehicle before connecting the nozzle; inflate tyres with dry nitrogen and check them cold. Dye penetrant finds surface-breaking cracks (clean, penetrant, dwell, remove, develop, inspect); magnetic particle needs ferromagnetic parts and demagnetising afterwards; eddy current finds surface and near-surface defects in conductors; ultrasonics need a couplant. After lightning strikes, heavy landings or severe turbulence, follow the manual's special inspections.

Procedures

Parts need proper release documents such as an EASA Form 1; unserviceable parts go to quarantine; deferred defects follow the MEL; critical tasks such as flight controls get independent inspections; the CRS confirms the work was done to approved data.