The Part-145 man-hour plan audit: the five numbers a surveyor asks for first

I've sat on both sides of a Part-145 survey — as the engineer whose hangar is being audited and as the instructor brought in after the findings land. The pattern never changes: the surveyor doesn't read your man-hour plan cover to cover. They sample it. Within the first hour they ask for five specific numbers, and whether those numbers exist — and agree with each other — decides whether the audit takes two days or two weeks. Here's exactly what they ask for, and how to have it ready.

01Planned man-hours by type and month

Under AMC1 145.A.30(d), your man-hour plan must show that staffing matches the anticipated workload. The surveyor's first question: "Show me next quarter's planned man-hours, split by aircraft type." Not a total. If your AW139 base check input is 1,500 man-hours in April and your AW169 input is 900 in May, those need to appear as separate line items with the utilisation forecast that produced them. A single annual total on a spreadsheet is the fastest way to a level-2 finding for "planning process not effective."

02Actual vs planned — with the deviation worked out

Second question: "And what did you actually use?" The surveyor is testing whether the plan is a living document. The check they run is the deviation calculation:

Worked example: your plan called for 4,800 man-hours in Q3 across the fleet. Timesheets show 6,150 man-hours booked:

Q3 breaches the commonly applied 25% deviation threshold. That isn't automatically a finding — the finding is when you breach it and have no recorded re-plan. The surveyor wants to see that the deviation triggered a review, a root cause (an unplanned AW189 gearbox change doubled the input), and a revised plan. The deviation is evidence of reality; the missing re-plan is evidence of a broken process.

03Certifying staff as a ratio of total staff

Third: "Of the people in that plan, how many hold certification authorisation, by category?" The plan must demonstrate that certifying coverage — B1 and B2 separately — matches the task split. If 60% of your man-hours are airframe tasks but only one of your five engineers can certify B1, the plan fails on paper even if the total headcount looks fine. Have the ratio table ready per type, per shift.

04The five-number audit checklist

Numbers 4 and 5 are where audits are actually lost. Everyone has a plan; almost nobody can prove the plan was reviewed and re-issued when reality moved, or that it was built on the CAMO's current forecast rather than last year's.

05Build the audit file before the audit

The fix is boring and cheap: once a quarter, export the plan, run the deviation table, write three sentences of commentary, file it. Twenty minutes per quarter produces a two-year evidence trail that makes the surveyor's sampling exercise a formality. If your planning lives in a spreadsheet that only one planner can read, move it into a tool that produces the planned-vs-actual comparison and an auditor-ready PDF on demand — that's the difference between defending your plan and just showing it.