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failure of the engine itself or an engine mount issue, with the possibility the vibration could tear the engine off its mounts. A strong vibration might also break hoses or fuel lines and lead to a fire. So, any wild vibration of a propel- ler or engine is grounds for a precautionary shutdown. You certainly would not want to land trying to manage this vibration when it could impair control or suddenly develop into a catastrophic condition close to the ground.
The condition need not be dramatic for you to at least consider a precautionary shutdown. If something just isn’t working right with an engine or propeller, you might decide to shut it down and feather the propeller to pre- vent damage or at least additional damage. This is less obvious than the other scenarios and may open you up to criticism if it turns out the condition wasn’t as bad as you thought. But don’t listen to the nay-sayers. It may be hard to determine exactly how bad something is in the air. It’s always better to troubleshoot on the ground, so a precautionary engine shutdown is an option.
So, oil loss, overspeed, vibration, or something else prompts you to perform a precautionary shutdown. Just perform the Precautionary Engine Shutdown checklist, right? Except many Airplane Flight Manuals or Pilot’s Operating Handbooks (AFMs/POHs) do not provide one. We can, however, co-opt the Engine Fire in Flight check- list for this purpose. The Beech Baron 58 Engine Fire in Flight checklist, for example, reads:
In Flight
Shut down the affected engine according to the following procedure and land immediately. Follow the applicable single-engine procedures in this section.
1. Fuel Selector Valve – OFF
2. Mixture Control – IDLE CUTOFF 3. Propeller – FEATHER
4. Fuel boost pump – OFF
5. Magneto/Start Switch – OFF
6. Alternator Switch – OFF
If all you do from memory is to shut off the fuel selec- tor, pull the mixture control and feather the propeller (being very careful to pull the correct prop handle), you can transition to and trim for single-engine flight, then reference the checklist to “clean up” by performing the remaining checklist steps.
Air Start
On the other end of the engine spectrum, from an inflight precautionary shutdown, is an air start. That is, taking an engine you shut down for some reason (or that shut down on its own) and firing it back up. For that, most AFMs/POHs do have a checklist in the Emergency Procedures section. For our example Baron 58, this checklist directs:
AIR START
Caution: The pilot should determine the reason for engine failure before attempting a restart.
1. Fuel Selector Valve – ON
2. Throttle – SET approximately 1⁄4 travel 3. Mixture Control – FULL RICH
4. Fuel Boost Pump – ON
5. Magnetos – CHECK ON
6. Propeller:
WITH UNFEATHERING ACCUMULATORS
a. Move propeller control forward of feathering detent until engine obtains 600 rpm; then back to detent to avoid overspeeding. Use starter momentarily if necessary to accomplish unfeathering.
b. If propeller does not unfeather or engine does not turn, proceed to WITHOUT UNFEATHERING A CCUMULATORS procedure.
WITHOUT UNFEATHERING ACCUMULATORS
a. Movepropellercontroltofulldecreaserpm.
b. Engage Starter to accomplish unfeathering.
c. Ifenginefailstorun,clearenginebyallowing it to windmill with mixture in IDLE CUT- OFF. When engine fires, advance mix- ture to FULL RICH.
7. When Engine Starts – ADJUST THROTTLE, PROPELLER and MIXTURE CONTROLS
8. Fuel Boost Pump – OFF (when reliable power
has been regained)
9. Alternator Switch – ON
10. Oil Pressure - CHECK
11. Warm Up Engine (approximately 1500 rpm
and 15 in. Hg)
12. Set power as required and trim.
That’s a fairly complex procedure. The good news is that none of it must be done from memory. If you’re performing an air start, you’re already under control in single-engine flight. When you’re ready, pull out the checklist, review it before actually performing checklist steps, and then read a step and do a step until the engine has restarted.
So when would you perform an air start? The key is in that caution at the top of the checklist: only if you know why the engine was shut down in the first place. More importantly, only if you know the engine should start back up and run properly.
This means you would only perform an air start if you had shut the engine down yourself for something other than a known or suspected mechanical reason. In
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