Propellers

This guide is for propellers and their governors, spinners and de-icing systems, bought new on an aircraft or bought as a change to one already flying. The engine that turns it is in the turbine and piston engine guides. The overhaul shop that opens it is in MRO. What sits here is a product with a type certificate of its own, and buyers who treat it as an engine accessory get the certification and the cost model wrong in the same move.

What the standard actually requires

Part 35 prescribes the airworthiness standards for issuing a propeller type certificate and for changes to it, and its structure tells a buyer where the risk sits.¹ The part requires instructions for propeller installation and operation, ratings and operating limitations, and instructions for continued airworthiness.¹ It identifies propeller critical parts, whose failure the design must be shown to guard against, and it sets requirements on materials and manufacturing methods, on durability and on variable and reversible pitch mechanisms.¹ Read that list as a question set. Which parts on this propeller are critical parts, what are their approved lives, and what does the installation and operation instruction require of the engine and airframe combination you are actually flying.

The three-way fit is the purchase

A propeller is approved for an installation, not in the abstract. Ask for the propeller model, the engine model and the airframe model as one line, and ask what approval covers that combination: the aircraft's own type design, or a supplemental type certificate somebody holds. Ask about the operating limitations that come with the fit, including any restricted RPM range, because a placarded avoid range is a real operational cost on a training fleet. Ask what the propeller does to noise and to takeoff performance in the configuration you fly, and ask for the data rather than the claim.

The economy is overhaul, not purchase

Propellers are bought once and overhauled repeatedly. Ask for the published overhaul interval in hours and in calendar time, and ask which of the two will bind first at your utilisation. Ask what an overhaul costs today, what an unairworthy blade adds to it, and what the hub replacement costs when corrosion is found. Ask where the approved shops are, because a propeller shipped across a continent twice is a longer downtime than the shop's quoted turn time. Repair station ratings are explicit here: class 1 covers fixed-pitch and ground-adjustable propellers of wood, metal or composite construction, and class 2 covers other propellers by make.² A shop rated for class 1 is not a shop for your constant-speed unit.

Where the record can be checked

Propeller type certificates, parts manufacturer approvals and technical standard order authorisations are published and searchable, so a supplier's approval claim can be confirmed before a purchase order.⁴ That check proves the approval exists and what it covers, and proves nothing about condition or lead time. Airworthiness directives apply to propellers by name, and the FAA issues one when an unsafe condition exists in a product and is likely to exist or develop in others of the same type design.³ Search the propeller and the hub separately from the airframe, and ask for the compliance record on the serial numbers being offered.

Questions that sort suppliers

Ask which approval covers your exact propeller, engine and airframe combination. Ask for the critical parts list, the life limits and what remains on the units offered. Ask for the overhaul interval, the current price and the last three actual turn times. Ask what a blade strike costs, in money and in weeks.

The companies below are listed on public facts, each with its source linked.