Page 21 - Volume 11 Number 10

broke, flinging off the sleeve and freeing the propeller. “Hell, that worked. We need to get moving. Sit down and buckle up.” And with that, the PIC fired up the left engine, burned its restraint off, and proceeded with the flight!
(This story was related to me by the copilot. Names have been changed to protect the not-so-innocent. I never found out if the boss made his appointment!)
I learned from that incident that (1) You need some visual reminder that the restraints are installed. (2) The engine starts satisfactorily with the fabric exhaust covers on, not reaching excessive ITT. (3) Never be in such a hurry!
Now on to the blade up versus blade down argument. In the days of nothing but three-blade propellers, there was – and still is for those with three-blades – a “correct” answer: Down. This is true for two reasons. First, the shape of the exhaust covers and the angle at which the elastic straps connect to them permit the stack cover to fit perfectly when the strap comes upward to the cover. If the strap angles downward the exhaust cover can be forced to fit, but it is obviously not designed with that position in mind. Second, why was it designed this way? So that rain could drain out of the spinner through the hole for the down
blade. There were incidences reported of noticeable propeller vibration and it was traced to water that had collected in the spinner, turned into ice as the temperature dropped, and left that ice slug inside the spinner, upsetting the balance.
The main reason that a lot of pilots prefer the blade up orientation is to make the restraint more obvious from the cockpit – less of a chance of making the “Start with ’em on” mistake. With the four-blade propellers, of course there will be a hole for rain to exit the spinner no matter whether the sleeve connects to the down or up blade. Thus, putting the sleeve on the up blade does not increase the risk of propeller imbalance due to ice inside the spinner. However, the fit of the strap and cover to the exhaust stub still favors the blade down profile ... leading me to still use the original orientation. But I have no complaint whatsoever for those who choose to go blade up position for the increased visibility reason.
Ready for another war story? Because of the delay needed to wait for the exhaust stack to cool enough for comfortably installing the stub covers, this particular operator had made a second set of prop restraints that replaced the elastic cords and the stub covers with simple bungees with hooks on both ends ... one
OCTOBER 2017
KING AIR MAGAZINE • 19