This test would be to test the turbo system, and other engine settings, mainly throttle. I also wanted to check to see if my magnometer issue returned from the last flight, where I experienced a mismatch.
The startup was quite normal, but right away I noticed the very high Idle setting of 1050rpm. I will need to adjust that once I return. I taxied out, performed a runup and ATC cleared me to taxi to runway 32, ideal for a “adjusted engine” take off. Another short runup was performed and no magnometer mismatch this time.
I decided to stay in the pattern for at least one circuit before I would venture away from the airport. I was cleared for take off following a slow archer. I added T/O power, and I got 28.4” manifold pressure, pretty nominal. Halfway in the roll, at 40 knots, I turned the turbo switch to ON. Manifold pressure responded and I received 29.6” pressure. Other engine parameters were as expected.
Airborne at 80 kts, nose wheel at 75kias. Accelerated to 100 kias, and climbed with 900 ft/min to 2000ft, for a faster circuit to see how the engine performed. I requested a low approach, approved and started my descend back down. All the while manifold remained at 28.9”, a little higher but it made me smile.
After the low approach and initial climbing I requested a turn to the east, and was approved via a Right turnout. I continued the climb and stayed just below the class C until passing the boundary and continued the climb, while maneuvering a little more north for inbound traffic to the field.
At 2500 ft I started to notice that the manifold pressure was diminishing slightly. By the time I got to 4000ft MSL, I was down to 26.7” MP. Clearly I was still losing pressure. No Eureka moment..yet.
I flew a little longer and tried turning the turbo switch ON and OFF, and measuring differences in MP. There seemed to be no pressure increase at all..
I landed after 0.7hrs airborne and shut down at the hangar. I would be down to my last option, that I know to check.
Sieders Family Velocity Aircraft 