Hi David,
I’m sure others will offer their opinions however for what it’s worth, here’s mine.
The way I read the Operators Manual, both RPM and Manifold Pressure have a 5 minute time limit when above their maximum continuous limits.
On page 2-2, the performance table states “take-off performance” as 85.4kW at 5800RPM and 39.0”HG (later TCU).
On page 2-3, the limits for each parameter are stated separately.
The RPM limit is explicitly stated as “Take-off speed” - 5800 for 5 minutes maximum.
This implies (to me anyway) - ANY RPM above 5500 is limited to 5 minutes with 5800 being the absolute maximum.
The Manifold Pressure (to my way of interpretation due to a maximum continuous limit being stated), is the same 5 minutes at “Take-off performance”.
This implies (again, to me) - ANY MAP above 35.4”HG is limited to 5 minutes with 39.9”HG the absolute maximum.
Therefore after 5 minutes at an RPM and/or MAP above the maximum continuous limit for either parameter, the maximum CONTINUOUS limits apply - RPM (5500) and Manifold pressure (35.4”hg).
If your MAP is decreasing from 39ish”HG to below 35.4”HG during climb after take-off within the 5 minutes then all is good. My belief is RPM limits are not monitored by the TCU warning lights. Some pages from the MMH attached re the operation of the boost light.
I’m happy to be proven incorrect.
Cheers,
Des.
