4 Tips to Simplify Your Regional Turboprop Engine's Return to Service

By Pratt & Whitney Customer Service

Bringing regional turboprop engines back into service after a period of inactivity should be a simple, trouble-free process. See tips from our experts below.

1. Store the Engine Properly.

As the aviation sector continues to recover from the effects of the pandemic, many aircraft are returning to service after being grounded for months. With international travel still facing restrictions, regional aircraft are leading the way thanks to their size, versatility, efficiency and reliability as the global travel industry for both business and pleasure continues to climb back to more normal levels.

Simplifying the process of bringing your regional turboprop engines back into service starts when you put them into storage. There are some important steps to follow if your engine will be inactive for an extended time.

As covered in a previous Airtime article, depending on the duration of inactivity and the engine model, these may include:

  • purging the existing fuel and replacing it with preservation oil.
  • preserving the oil system.
  • placing desiccant bags in the engine.
  • sealing the engine’s openings.
  • performing a desalination wash.

For full details, consult your Engine Maintenance Manual (EMM), the definitive source of information for all the procedures.

2. Check on the Engine While in Storage.

When putting the engine in storage, decide whether you will run it periodically or leave it inactive for a predetermined period. This will impact both the storage procedures and the actions to take while it’s in storage, as explained in the EMM.

If you run the engine periodically, do so every one or two weeks, depending on the engine model, says Camilo Rendon, Senior Manager, Service Engineering, PW100 Regional Turboprop, Pratt & Whitney Canada.

Remove the covers and run the engine until the oil system meets certain parameters, then shut it down and put the covers back on again. Every 30 days you should check the engine externals for corrosion and analyze the oil to ensure it’s lubricating the system properly and is not too acidic.

- Camilo Rendon, Senior Manager, Service Engineering, PW100 Regional Turboprop.

Running the engine periodically may involve more effort during storage than preservation for a pre-determined amount of time, but it means the engine can quickly be ready for operation whenever you need it again.

Even if you opt for preservation, you shouldn’t simply leave the engine untouched for months. The aim of all the storage procedures is to protect the engine from corrosion. To control the humidity when storing, place desiccant bags for absorption inside the engine as well as a humidity indicator and seal the engine using a transparent cover so you can read the indicator easily.

While the engine is inactive, check the humidity level once a week. If it exceeds the threshold indicated in the manual (typically 40%), it’s time to open up the engine and reactivate or replace the desiccant bags.

Whether you have stored the engine indoors or outdoors, the process is the same. But if it’s located outside in a tropical or coastal area, for example, you will probably need to replace the desiccant bags more often.

- Camilo Rendon, Senior Manager, Service Engineering, PW100 Regional Turboprop, Pratt & Whitney Canada

3. Verify That the Engine is Ready to Return to Service.

Once it’s time to start using the engine again, there are several important steps to make sure it’s ready to fly.

The first is to ensure all the openings sealed previously are reopened and unobstructed, and that all the humidity indicators, desiccant bags and moisture barriers are removed.

Next, and depending on the period of storage, you will need to reactivate the oil and the fuel system and inspect for corrosion, which is the main concern after a period of downtime. If you find any corrosion, you will need to clean or repair the part as required.

Finally, run the engine. “When you store the engine for a long period of time, the recommended steps help to ensure that the engine will be service-worthy when it is required to return to service, so if you followed all the recommendations, you should be ready to fly again,” says Camilo.

Spare engine solutions 

4. Consider That Additional Steps May Be Required to Resume Flying.

It’s strongly recommended that you follow the engine preservation procedures in the EMM. However, if you were unable to do that, the return-to-service process will require additional steps – and possibly a shop visit.

If the engine was not stored according to the recommended procedures, we advise operators to reach out to us directly. We will evaluate each case separately. Based on the length of inactivity, the storage environment and other factors, we will recommend whether it can return to service or needs a light overhaul inspection first.

- Camilo Rendon, Senior Manager, Service Engineering, PW100 Regional Turboprop, Pratt & Whitney Canada

If the improper preservation lasted less than six months, it may be possible to resume flying after some specific actions. They include checking the oil system, changing the filters and external oil seals, internal borescope inspections and performing a series of run-ups to verify the integrity of the engine fuel and oil systems.

Even if it’s determined that a return to service is possible without a shop visit, the operator will still need to keep monitoring certain parameters for a determined amount of time.

If you have questions, contact your P&WC customer manager, field service manager or the CFirst Centre. They will help you ensure your engine is ready to fly again as quickly as possible.

For more tips on how to keep your engine in optimal condition, see 4 Maintenance Best Practices for Preventing Salt Air Corrosion.