GRPR. From the Piper PA-44-180 Seminole Information Manual - Section 10 Safety Tips Report
VB-860 issued March 23 1978.
Paragraph (l): "Experience has shown that the training advantage gained by pulling a mixture control or turning off the fuel to simulate engine failure at low altitude, is not worth the risk assumed, therefore it is recommended that instead of using either of these procedures to simulate loss of power at low altitude, the throttle be retarded slowly to idle position. Fast reduction of power may be harmful to the engine. A power of 2000rpm and 11.5 Hg MAP is recommended for simulated one engine operation". End of quote.
The first few words "Experience has shown" says it all.
Now put yourself in the Coroners Court with a cold eyed barrister asking you why you pulled the mixture which caused the aircraft to yaw badly due to slow reaction by your unfortunately maimed student now in hospital.
"Because it is good for the engine, Sir" you reply.
" Oh really, Mr Grade One Instructor - how interesting. Do you not accept the Piper recommendation at Para (l) of the PA44 Information manual that pulling the mixture etc is not worth the risk assumed?" says the barrister, who has the manual in front of him and knows he has you by the short and curly.
"No Sir, I do not accept the Piper recommendation because I am a good instructor with lots of confidence that I can get out of trouble if the student cocks up. I have done this many times, therefore it must be safe. The student just stuffed up, that's all. It wasn't my fault".
Do you get the message? I do, because I have been to a Coroners Court and I have seen a chief pilot torn to shreds by counsel for the dead. The aircraft flight manual was used to hang the instructor, and quite rightly so.
Pulling the mixture is foolhardy, and not worth the risk to your student.