Part 135 maintenance: what changes when you fly for hire.
A plain-English guide to the maintenance rules for on-demand and commuter operators, from the 9-seat line to service difficulty reports. Use it as a checklist, then let MRO Tracker keep the aircraft and the dispatch desk in step.
The certificate holder is responsible
Under 14 CFR 135.413, the certificate holder is primarily responsible for the airworthiness of its aircraft, including airframes, engines, propellers, rotors, appliances and parts. You can contract the work out, but not the responsibility.
Which maintenance rules apply depends on one number: the passenger seats on the aircraft's type certificate, not counting pilot seats (135.411).
Nine passenger seats or fewer
Part 91 and 43, plus more
These aircraft are maintained under Parts 91 and 43 and the added Part 135 rules listed in 135.411(a)(1).
Annual and 100-hour, or an AAIP
Because you carry people for hire, the 100-hour inspection under 91.409(b) applies on top of the annual. Instead, you can use an approved aircraft inspection program under 135.419, which goes into your operations specifications.
Manufacturer programs become required
Under 135.421, engines, propellers, rotors and each item of required emergency equipment follow the manufacturer's recommended maintenance program or an FAA-approved program. In practice, that is where the manufacturer's TBO stops being optional.
Ten passenger seats or more
These aircraft need a continuous airworthiness maintenance program, or CAMP, under 135.411(a)(2) and 135.415, 135.417 and 135.423 through 135.443. The main pieces are:
A maintenance organization able to do the work, in-house or by arrangement (135.423)
A maintenance manual and program covering inspections, overhauls and required inspection items (135.425, 135.427)
Required inspection items signed by a qualified inspector who did not do the work (135.429)
A continuing analysis and surveillance system (135.431)
A training program for maintenance people (135.433)
Maintenance records (135.439) and an airworthiness release or log entry before flight (135.443)
Discrepancies, the log and the MEL
Under 135.65, the pilot in command records every mechanical irregularity found during flight time in the aircraft maintenance log, and checks the log's status before each flight. The corrective action, or the deferral, is entered against the item.
Flying with inoperative equipment needs an approved minimum equipment list under 135.179, authorized in your operations specifications. Each deferral has a repair interval, and the aircraft is not dispatched past it.
The practical rule: one log per aircraft that the pilot, the mechanic and the dispatcher all look at.
Reports you owe the FAA
Service difficulty reports
Under 135.415, report the failures, malfunctions and defects the rule lists, such as fires, engine shutdowns, flight control problems and structural cracks, to the FAA within the 96-hour window the rule sets.
Mechanical interruption summary
Under 135.417, send a monthly summary of flight interruptions, unscheduled aircraft changes, and unscheduled stops and diversions caused by mechanical problems, by the 10th of the next month.
Both are easier when every squawk, deferral and AOG event is already in one place with dates and ATA chapters.
The records you must keep
Under 135.439, keep these for each aircraft and transfer them when it is sold:
Total time in service of the airframe, engines, propellers and rotors
Current status of life-limited parts
Time since last overhaul of items overhauled on a time basis
Current inspection status, including time since each inspection your program requires
Current AD status, with dates and methods of compliance, and the next due point for recurring ADs
A list of current major alterations and repairs
Records of the work itself, with the signature of the person approving the return to service, are kept for at least one year or until the work is repeated or superseded.
How MRO Tracker keeps you dispatchable
Maintenance and dispatch on one record
An overdue inspection, an overdue AD or an overdue MEL deferral marked to block dispatch stops bookings and releases until it is signed off, with a live list of what is blocking.
Squawks from check-in to closure
Pilots log squawks at check-in, straight to the aircraft's discrepancy log. A corrective action closes the item, a deferral stays open under the MEL, and grounding squawks alert dispatch.
ADs and programs read for you
New US ADs are matched to your aircraft, engines, props and APUs daily, and your inspection program can be read from the manual for you to approve task by task.
AOG to return to service
Each aircraft-on-ground event runs through troubleshooting, parts and return to service, with every change on its timeline.
Pricing: Maintenance is $95 per aircraft a month ($150 for jets). Operations, with scheduling, releases, FRAT and crew, is $195. MRO Tracker for Part 135 · See pricing
Common questions
Does a Part 135 aircraft need a 100-hour inspection?
For aircraft with nine passenger seats or fewer, yes, along with the annual, unless you use an approved aircraft inspection program under 135.419. Aircraft with ten or more seats follow a CAMP instead.
Can I fly past engine TBO under Part 135?
Not on your own say-so. Under 135.421 the engine follows the manufacturer's program or an FAA-approved program, so running past TBO needs an approved extension.
Can our pilots do preventive maintenance?
The general pilot-owner permission in 43.3(g) does not cover aircraft used under Part 135. Narrow exceptions exist under 43.3(h) and (i), and they need FAA approval and training under your program.
Who decides an item can be deferred?
Your MEL and your manual. The MEL sets the conditions and the repair interval, and your procedures say who may sign the deferral.
How is this different from Part 91?
Under Part 91, service bulletins and TBOs are mostly recommendations and there are no reports to file. Under Part 135, manufacturer programs, the maintenance log, the MEL, reporting and record transfer all become part of your certificate.
This guide is a summary for planning, not legal or maintenance advice. Check the current regulations, your operations specifications and your manuals before relying on it.
See also the Part 91 and Part 145 guides, or start a 14-day free trial and book a demo.