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a version of which is used on the King Air B100. All 331s also use a P3 fuel purge system, but theirs is a bit more complex with a normally- closed solenoid valve involved. When the shot of P3 air purges the fuel manifolds at shutdown, it causes so much fuel to be sent through the nozzles that engine speed actually increases noticeably before it starts to decrease. This phenomenon rarely if ever happens with the PT6. No N1 surge will be seen. What will be observed, however, is a momentary delay between pulling the Condition Lever and seeing N1 start to decrease...maybe just a half- second. It’s short but noticeable, and something that is not observed with the older collector tank system. If you do not experience the delay, you did not get a good purge and may expect to see some smoke.
I hope this discussion has increased your understanding of these systems and will help in troubleshooting any problems that may occur. KA
Correction: My article that appeared in the August 2015 issue of King Air discussed Pressuriza- tion System Abnormalities. One of the components I reviewed was the Preset Solenoid valve, and I stated that it was installed on C90 and later King Air models. No, it made its appearance with the introduction of the B90 in 1968; LJ-318 and after all have Preset Solenoids.
About the Author: King Air expert Tom Clements has been flying and instructing in King Airs for over 43 years, and is the author of “The King Air Book.” He is a Gold Seal CFI and has over 23,000 total hours with more than 15,000 in King Airs. For information on ordering his book, go to www.flightreview.net. Tom is actively mentoring the instructors at King Air Academy in Phoenix.
If you have a question you’d like Tom to answer, please send it to Editor Kim Blonigen at kblonigen@ cox.net.
NOVEMBER 2015
KING AIR MAGAZINE • 19