Q1. PFLs in Fuel Injected engines, and 'warming' the engine?

[Roller44]

Hi all,

To answer the Q, is it a good idea to warm the engine for fuel injected types during a PFL, I can help by stating the current practice as taught at the ADF BFTS, in the IO-360 HP equipped CT4B’s.
We teach a variety of simulated engine emergencies, however the simplest “flame out” case has us initially select idle power, and configure for the 80KIAS glide, followed by an evaluation, which simple looks for the presence of fire/ smoke.
After this, we select the “practice” case power setting of 10-11” MAP, and half flap to mimic the handling ROD’s and attitudes expected from a real failure, and then would follow a continuation of our IA’s. The slight increase in power slows the cooling and helps to stabilise engine performance.

During the descent, part of the work cycle is to monitor CHT, and this is reinforced in our Student Training guide so at specific points in the pattern the CHT is called and, if it is close to or at the specified minimum CHT value of 115C, the procedure is to suspend the PFL and conduct a “Warming orbit” at 20”MAP for as long as it takes to raise the CHT to a reasonable working value, such as 140-150C. We then recommence the pattern from the knock off point until either the PFL is terminated or it’s time for the next warming orbit. From 7000’ it may be we would need to repeat this 3 or 4 times.
This saves the engine, but does have the result of a fairly dislocated procedure, especially in the dead of winter, when we may need to perform the first warming orbit as little as 60 seconds after the initiation of the PFL. So far, our failure rate of engines due to cracked heads/ valve seats are negligible. Food for thought?