Airframe and Powerplant Rating Scope of Work Differences

When the FAA issues an Aviation Maintenance Technician (AMT) certificate, it comes with one or both of two ratings: Airframe and Powerplant. Each rating is a legally separate grant of authority, and the scope of work a technician may perform — and, crucially, return to service — is strictly defined by which rating that individual holds. A mechanic who holds only the Airframe rating may not approve powerplant work for return to service, and vice versa. Understanding these boundaries is not merely a test requirement; it is a professional and legal responsibility that directly affects airworthiness and passenger safety.

This article walks through what each rating covers, where the line falls between them, what happens when one person holds both ratings, and the edge cases the FAA knowledge test loves to probe.

Legal Foundation: 14 CFR Part 65

The privileges and limitations of AMT certificates and ratings are established in 14 CFR Part 65, Subpart D. Section 65.81 states the general rule: a certificated mechanic may perform or supervise the maintenance, preventive maintenance, and alteration of an aircraft or appliance — but only for the specific rating(s) held, and only when the work is consistent with the applicable airworthiness standards and data. Section 65.85 details the Airframe rating privileges, and Section 65.87 details the Powerplant rating privileges. The authorization to return an aircraft to service after maintenance (by signing the maintenance record) is perhaps the most important practical privilege each rating conveys.

Airframe Rating: Scope of Work

The Airframe rating authorizes the holder to perform maintenance, preventive maintenance, and alteration on the structural and non-propulsion systems of the aircraft. In practical terms, this encompasses an enormous range of work:

Aircraft structures: Fuselage, wings, empennage (tail surfaces), control surfaces (ailerons, elevators, rudders, flaps), spars, ribs, and skin panels — whether made of aluminum alloy, steel, wood, fabric, or composite materials.
Landing gear systems: Retraction mechanisms, shock struts (oleo struts), wheels, brakes, and associated hydraulic systems that serve the landing gear.
Flight control systems: Cable runs, pulleys, bellcranks, push-pull rods, and trim systems that connect the cockpit controls to the control surfaces.
Hydraulic systems: Hydraulic actuators, reservoirs, pumps, and lines that are part of the airframe (as opposed to engine-driven hydraulic pumps, which overlap into the Powerplant area).
Pneumatic systems: Pressurization systems, de-icing boots, and associated plumbing mounted in the airframe.
Fuel systems: Fuel tanks, fuel lines throughout the airframe, fuel selectors, and vents — up to the point where fuel enters the engine's fuel control system.
Electrical systems: Aircraft wiring, buses, switches, lights, and avionics installations within the airframe structure.
Cabin and interior: Seats, seat rails, emergency equipment, windows, doors, and soundproofing.
Rotorcraft airframe components: Rotor hubs, blades, and associated controls are considered part of the airframe on helicopters.

The Airframe rating holder signs off on an FAA Form 337 (Major Repair and Alteration form) for eligible airframe work, and makes the return-to-service entry in the aircraft's maintenance records per 14 CFR 43.9 and 43.11. However, an Airframe-only mechanic cannot return an aircraft to service after an engine overhaul or propeller work — that requires the Powerplant rating.

Powerplant Rating: Scope of Work

The Powerplant rating authorizes maintenance, preventive maintenance, and alteration of aircraft engines and propellers, along with the systems closely tied to engine operation. This includes:

Reciprocating engines: Cylinders, pistons, crankshafts, camshafts, magnetos, carburetors, fuel-injection systems, and engine-driven accessories (alternators, vacuum pumps, oil pumps).
Turbine engines: Compressor sections, combustion chambers, turbine sections, fuel control units, and thrust reversers on turbofan/turbojet engines; turbine engines on turboprop aircraft as well.
Engine mounts: The mounts that attach the engine to the airframe are generally considered part of the powerplant installation. This can be a source of confusion — the mount itself sits at the intersection of both ratings. FAA guidance treats the engine mount as part of the powerplant system for return-to-service purposes.
Propellers: Fixed-pitch, constant-speed, and feathering propellers; propeller governors; de-icing systems integral to the propeller.
Engine fuel system (powerplant portion): Fuel pumps, fuel control units, fuel nozzles, and the lines from the firewall to the engine.
Engine oil system: Oil coolers, oil lines, breather tubes, and oil sumps.
Exhaust systems: Exhaust pipes, mufflers, heat exchangers, and turbocharger exhaust components.
Engine induction and cooling systems: Intake scoops, cowl flaps, baffles, and intercoolers.
Ignition systems: Magnetos, harnesses, spark plugs, and ignition switches connected to engine operation.

A Powerplant-only mechanic may run up and test an engine and sign off the maintenance records for all of the above, but cannot approve structural airframe repairs or avionics work in the airframe for return to service.

When One Technician Holds Both Ratings

Many AMTs earn both the Airframe (A) and Powerplant (P) ratings — commonly called an A&P certificate. Holding both ratings does not create a new, combined rating; rather, the holder simply enjoys the full combined privileges of each rating independently. An A&P mechanic can return an entire aircraft to service after performing or supervising work in either domain. This is the most common and versatile credential in the field, and most aircraft maintenance positions require it.

It is important to note that even an A&P mechanic cannot approve major repairs or major alterations for return to service without an Inspection Authorization (IA). The IA is a personal authorization: it cannot be exercised by proxy, and a mechanic does not gain the authority to approve a major repair, major alteration, or annual inspection for return to service merely by working near or under the general direction of someone who holds an IA. Only the IA holder may personally make that approval. The IA is an additional authorization — not a rating — issued under 14 CFR 65.91. Without an IA, even the most experienced A&P mechanic cannot independently approve a major alteration or return an aircraft to service after an annual inspection.

Overlap Zones and Gray Areas

Some aircraft systems straddle the boundary between Airframe and Powerplant, and knowing how the FAA draws the line is critical for exam purposes:

Engine firewall: The firewall is generally considered the dividing line for fuel and oil lines. Lines from the tanks to the firewall are airframe; lines from the firewall to the engine are powerplant.
Engine-driven pumps: A hydraulic pump driven by the engine is maintained under the Powerplant rating even though it serves the airframe hydraulic system.
Cowling: Engine cowling is considered part of the powerplant installation, so cowling repairs fall under the Powerplant rating.
Fire detection and suppression: Engine fire detection systems are generally part of the powerplant installation; however, cabin smoke detectors are airframe work.
APU (Auxiliary Power Unit): An APU is treated as a powerplant and requires the Powerplant rating for return-to-service approval.

Key Numbers and Rules

14 CFR 65.81: General privileges and limitations for certificated mechanics.
14 CFR 65.85: Specific Airframe rating privileges.
14 CFR 65.87: Specific Powerplant rating privileges.
14 CFR 43.9 and 43.11: Requirements for maintenance record entries, including the return-to-service statement that both Airframe and Powerplant holders make after eligible work.
14 CFR 65.91: Requirements for the Inspection Authorization (IA), which is required for annual inspections and approving major repairs/alterations for return to service.
Neither rating alone is sufficient to conduct an annual inspection; an IA is always required for the annual.
A mechanic certificate does not expire, but the privileges require the holder to remain current and competent; there is no biennial renewal requirement for the AMT certificate itself (unlike a pilot certificate).

Common Test Traps

Trap 1 — Return to service vs. performing work: A mechanic with an Airframe rating can perform many maintenance tasks on an aircraft, but the key legal privilege is the authority to approve that work for return to service. The test often asks which rating is needed to make the sign-off, not just who can turn the wrench.
Trap 2 — Cowling is Powerplant: Many students assume cowling is airframe because it is a structural cover, but FAA guidance treats engine cowling as part of the powerplant installation — a Powerplant rating is required to approve cowling repairs for return to service.
Trap 3 — Annual inspections require an IA, period: No matter how many ratings a mechanic holds, an A&P without an IA cannot approve an aircraft for return to service after an annual inspection, and that authority cannot be borrowed through the supervision of an IA holder — only the IA holder can personally make that approval. The test frequently pairs this with questions about 100-hour inspections, which a certificated A&P mechanic can perform and sign off without holding an IA.
Trap 4 — Engine mounts: Students sometimes assign engine mount work to the Airframe rating because mounts attach to the airframe. In practice, engine mounts are considered part of the powerplant installation for return-to-service purposes.
Trap 5 — Propeller is Powerplant, not Airframe: The propeller — including fixed-pitch propellers — falls entirely under the Powerplant rating. Even though the propeller is physically the frontmost part of many aircraft, it is legally part of the powerplant system.

Mastering the boundary between the Airframe and Powerplant ratings is fundamental to working legally and safely as an AMT. Each rating is a distinct grant of authority from the FAA, and signing off work outside your rating is not only a regulatory violation under 14 CFR Part 65 — it can compromise airworthiness and expose you to certificate action. Know your rating, know your limits, and when in doubt, check the applicable maintenance manual and consult the appropriate authority before making any return-to-service entry.