davidm767
Pre-takeoff checklist
Folks,
Just a short question that may not get an answer without someone actually looking into the engine.
Today I flew our school's problem child...a C172RG that just had its carb replaced (no idea if it was overhauled or actually no-kidding replaced). It had about 7 hours since it went through annual/carb replacement and hasnt had many issues since then. That is until today.
I went to the end of runway to perform the Mag check...the right one failed (300rpm)...I did a clean up, still no effects. Tried it again with mixture slightly leaner than before for another minute making sure I didnt toast the cylinders. Seemed to do the trick, but still not ideal with full mixture (barely passed).
I elected to stay tight in the pattern, mostly because of the aircraft's mag problems in the past (along with carb). On takeoff, I requested a short delay, did another full power static...things were normal no red flags. That is until the upwind after gear retraction and noticed the climb was sluggish, too sluggish (400fpm at S.L.) for the RG. Did a quick power instrument pack check noticing that oil temp, oil pressure were good, fuel pressure good, MP and RPM good, but CHT (single probe) was pegged past redline. NOT GOOD. I immediately pulled power to 1200 rpm, requested an immediate landing, and within 30 seconds the CHTs quickly came back online in the green.
After turn off and shutdown at parking the cowling was toasty with visible heat rising (South Florida temps were 85F). Needless to say, CHT's indication was real and not just a faulty gauge reading. Checked engine block for any oil spillage, none seen, check levels after leaving it nose into the wind for 10 minutes, nominal (.5Qts lower than before...but not a concern due to oil was still hot and likely in other places in the block (like cooler, pistons, etc))
With that in mind, knowing that this was quickly on its way to a possible if not probable engine failure...what could have caused excessively high CHT? We had normal oil levels, oil temps and pressure was good. So what would have starved the engine of enough cooling to keep it right of the green side (even if high from ground run ups)?
I'm more that curious since I'm on my way towards A&P certification (havent taken Power Plant yet, nor been schooled by a lot of old timers yet) I'd like to know what possible factors could cause this indication.
Speculation is welcome, although modest comments are appreciated. Having this aircraft been a problem child, I was expecting issues, just not this soon out of maintenance.
Just a short question that may not get an answer without someone actually looking into the engine.
Today I flew our school's problem child...a C172RG that just had its carb replaced (no idea if it was overhauled or actually no-kidding replaced). It had about 7 hours since it went through annual/carb replacement and hasnt had many issues since then. That is until today.
I went to the end of runway to perform the Mag check...the right one failed (300rpm)...I did a clean up, still no effects. Tried it again with mixture slightly leaner than before for another minute making sure I didnt toast the cylinders. Seemed to do the trick, but still not ideal with full mixture (barely passed).
I elected to stay tight in the pattern, mostly because of the aircraft's mag problems in the past (along with carb). On takeoff, I requested a short delay, did another full power static...things were normal no red flags. That is until the upwind after gear retraction and noticed the climb was sluggish, too sluggish (400fpm at S.L.) for the RG. Did a quick power instrument pack check noticing that oil temp, oil pressure were good, fuel pressure good, MP and RPM good, but CHT (single probe) was pegged past redline. NOT GOOD. I immediately pulled power to 1200 rpm, requested an immediate landing, and within 30 seconds the CHTs quickly came back online in the green.
After turn off and shutdown at parking the cowling was toasty with visible heat rising (South Florida temps were 85F). Needless to say, CHT's indication was real and not just a faulty gauge reading. Checked engine block for any oil spillage, none seen, check levels after leaving it nose into the wind for 10 minutes, nominal (.5Qts lower than before...but not a concern due to oil was still hot and likely in other places in the block (like cooler, pistons, etc))
With that in mind, knowing that this was quickly on its way to a possible if not probable engine failure...what could have caused excessively high CHT? We had normal oil levels, oil temps and pressure was good. So what would have starved the engine of enough cooling to keep it right of the green side (even if high from ground run ups)?
I'm more that curious since I'm on my way towards A&P certification (havent taken Power Plant yet, nor been schooled by a lot of old timers yet) I'd like to know what possible factors could cause this indication.
Speculation is welcome, although modest comments are appreciated. Having this aircraft been a problem child, I was expecting issues, just not this soon out of maintenance.
