Question about the MAP limits in SB-912-079 R1

Hi Jeff

That is a very good question.  The problem engines have primarily been with the 100 HP, 10.8 / 1 compression engines, that are carbureted.  A great deal of study has shown the inflight/constant speed are far more at risk.  The injected engines do however have temperature monitoring of the intake, this is a major factor in detonation. (high intake temps) The other major issue is excessive back pressure.  This primarily affects custom and OEM designed exhaust systems.  There currently is no call out that I have seen to verify this in the field at periodic intervals.  Exhaust baffles can and do fail, the result is normally detonation.  

I will make a few inquiries however, it i a valid question.  The SL was trying to address the bulk of failures seen, most are the carbureted engines.

If anyone is worried I would recommend to buy one grade better, more octane, fuel.  This should give you some peace of mind if you are not wanting to use 100LL or do not have access to the new unleaded avgas fuels. 

Cheers

At least in the northern lowlands, one reason for not just looking at rpm is that the winter density altitude can be way below sea level. On such day, it's quite possible to "overboost" at WOT early in the ground roll. Or, you might have a fixed pitch prop that's on a sleek airframe. A pitch fine enough to be WOT safe at low speeds may over-rev in level flight. A quasi-solution to both is to delay full throttle until later in the takeoff sequence. By 40-50 kt, even the rpm will likely be high enough and manifold pressure low enough to advance the throttle fully.