Page 26 - March 2023

standard propellers with their higher idle speeds, FOD became much too common!
The easy solution was to change the procedure such that ice vanes – now correctly called “engine anti-ice” on the later King Air models – were deployed for all ground operation. The location of the oil cooler in the pitot cowl causes oil cooling to not be negatively impacted due to engine anti-ice activation. Thus, there really was no downside risk associated with this new procedure of “ice vanes extended for all ground ops.”
Therefore, when this same FOD worry started affecting B200s of 1993 and after design – as well as earlier 200s and B200s that were now being retrofitted with four-blade props – the solution was easy ... copy the 300 technique and use ice vanes all the time while on the ground. Oops! What about that +15°C limit that applies to the 200-series but not the 300-series?
For a few years, the limitation was basically ignored. Personal
observation has convinced me that it is extremely rare for oil temperature to hit the maximum redline even in Phoenix, Arizona, in the summer months with a lengthy ground delay. Whew, I am happy for that! Then Beech got around to revising the POH and removing the +15°C limit. Now there is a “Note” in the “Before Engine Starting” section of the normal checklist that reads as follows: “The engine ice vanes should be extended for all ground operations to minimize ingestion of ground debris. Turn engine anti-ice off, when required, to maintain oil temperature within limits.”
If you, unlike I, do indeed find that you must turn engine anti-ice off because of hot oil, then avoid using beta and reverse even if it means riding the brakes at times.
Under the title of “Icing Limi- tations” found in Section 2 of the B200’s POH it states: “ICE VANES, LEFT and RIGHT, shall be extended for operations in ambient tempera- tures of +5°C or below when flight
free of visible moisture cannot be as- sured.” The next statement is: “ICE VANES, LEFT and RIGHT, shall be retracted for all takeoff and flight operations in ambient temperatures of above +15°C.”
It is obvious that FOD due to ground debris is not a problem in flight. It is also not a problem during takeoff unless the takeoff is aborted and reverse remains in use to too low of an airspeed. Hence, when doing the runway lineup procedure on warmer days, it is time to retract the vanes. Not only is better oil cooling assured but more takeoff power can now be achieved with less chance of being ITT-limited.
Now let’s examine the 300-series “Icing Limitations” found in Section 2 of its POH. This one is nearly identical to the 200, except for substituting “Engine Anti-Ice” for “Ice Vanes”: “ENGINE ANTI-ICE, LEFT and RIGHT, shall be ON for operations in ambient temperatures of +5°C or below when flight free of visible moisture cannot be assured.”
The next statement is: “ENGINE ANTI-ICE, LEFT and RIGHT, shall be OFF for all takeoff and flight operations in ambient temperatures of above +10°C.”
Do you notice what is different between the 300 and 200 in the second limitation? The ambient temperature got dropped by 5°: +10°C for the 300 and +15°C for the 200. Why the difference?
Since the pitot cowl of the 300 negates any oil cooling worry, the reason has nothing to do with the
oil cooler’s effectiveness. Rather, it comes from wanting to ensure proper takeoff performance. When there is no need for ice protection, why subject the engine to the slight power loss that goes hand- in-hand with ice vane deployment? The “Minimum Takeoff Power” numbers – from the graph in the Performance section of the POH – are based on the assumption that ice vanes will not be deployed during takeoff when unneeded.
In a similar manner, this helps explain the 300-series’ POH
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24 • KING AIR MAGAZINE
MARCH 2023