Questions to Ask Your Prop Shop

There can be significant differences in the experience level of technicians, and the sophistication of the processes and equipment used in the overhaul process from shop to shop. The answers that a prop shop provides to these questions should give you a better understanding of their capabilities and qualifications as well as what to expect.

Is the propeller repair station a member of Hartzell’s network of Recommended Service Facilities?

Hartzell’s network consists of shops that have been audited and meet Hartzell’s standards for quality, training, and tooling.  We recommend using these shops.

Does the shop maintain the required sample program approvals to perform critical required overhaul tasks?

Please visit our Sample Program Approval Listings page.

Have their technicians been properly trained?

Ask to see their training certificates. Hartzell offers several training classes for propeller repair technicians and provides certificates to those that have attended.

Are the non-destructive tests performed by certified Level II 
inspectors?

Ask to see the certifications.

What new parts will be provided in the overhaul price?

Price quotes can vary greatly from shop-to-shop. Compare what parts are included in each shop’s overhaul kit and insist that you are getting genuine Hartzell replacement parts.

What additional charges will be added to your invoice above and beyond the base rate quote amount?

Many shops’ base rate quotes do not include basics like shot peening and shank rolling, and some even charge extra for shop rags, lead removal, and balancing. The Hartzell Service Center’s quotes, for example, provide a clear summary of what is included, as well as a list of less common services which may require an additional charge. There will be no surprises when you get your final invoice.

When are the blade dimensional inspections performed? 


Many shops take measurements before they grind the blade but not after grind. While it’s a good idea to take measurements before grind, a dimensional inspection must take place after grind to ensure that the blade still meets the requirements of Hartzell Manual 133 before going back into service.

Will your aluminum blade be anodized or alodined?

Both processes are permitted. Alodine can provide corrosion protection comparable to anodize, but only if the alodine process used passes the 336 hour salt spray requirement.

What procedure does the prop shop use to perform shot peen?

Ask what procedure is used. Many shops do not use any procedure to control shot angle, intensity or duration. Shot peen is a critical operation to improve part fatigue resistance. Done incorrectly, it can actually damage the part and reduce fatigue strength. Ask the propeller shop if their shot peening is performed per Hartzell specifications, and is Hartzell-approved. Request to see their Hartzell certification.