Manifold Pressure Gauge Leak

JohnAJohnson

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JohnAJohnson
x-post from red...

Had an interesting problem the other day. Took off, had good power and terrific climb performance, then pushed over at 3000' AGL (3500' MSL) to level off and cruise around a bit. Got up to 140 MIAS quickly, then pulled the prop back to 2200 and MP back to 22, for a 65% cruise.

Banked it over and changed heading from south to west, and when I looked down at the heading during the rollout, noticed the airspeed at 85 MPH. Huh? I verified 22 square and should have been doing 127 MIAS or so. The attitude was slightly nose high, and I turned back to the airport. The airplane was acting as if it were iced up, loaded with a bunch of very fat people, or had a bunch of flaps out. Moving the throttle forward increased the MP of course, and I ran it at 25" till I was on downwind. Funny thing, the prop seemed to fall out of governing range too soon, at anything lower than 22" or so. I thought I might have a governor problem too. Landing was uneventful as I was way high and mostly glided from abeam the numbers in. Uncomfortable feeling believing you've got good power, but are still loosing airspeed.

Was all geared up to troubleshoot a pitot leak, but today, with the cowling off, I found the problem. The B-Nut for the MP Gauge tap-off on the #3 head, (above the intake runner) was completely backed out. Held on by less than a thread. Leaking like a sieve. Makes sense. This caused me to think I was running the engine at a higher power than it actually was running at, and the airplane was in fact moving slow, with the resultant high pitch attitude. Looking at the flight's EDM-700 data dump, EGT for #3 was no higher than normal, so it wasn't enough of an intake leak to cause any abnormal engine behavior.
 
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I had the tubing break on mine the other day. When I started to reduce power for cruise the guage did not respond it was just indicating altitude. I used airspeed (known for the RPM and MP) to adjust for this flight.
Thanks for the post here. I don't post on the red board.
I saw your post on the Red Board and realized that the partial failure with a leak could cause a different kind of problem. Instruments in conflict.
I don't have full engine instrumentation but , lean to rough and enrich to smooth. Engine didn't seem to mind at all.
 
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Yea, I'm usually reluctant to post on the red board too, but in this case, I thought I'd risk it in the hopes that it might help someone else out. I'm fully prepared for the obligatory idiot label, and to be told what all I should have done to troubleshoot, etc., had I been anything other than a half-assed pilot :)

It was such a strange malfunction (for me, at least) and in IMC, and enclosed in active headsets, I could see where it could really be dangerous. I recently installed an AOA system and looking back, it was telling me the straight skinny, but as it is new to me, I hadn't learned to rely on or trust it as much as I should.
 
Yea, I'm usually reluctant to post on the red board too, but in this case, I thought I'd risk it in the hopes that it might help someone else out. I'm fully prepared for the obligatory idiot label, and to be told what all I should have done to troubleshoot, etc., had I been anything other than a half-assed pilot :)

It was such a strange malfunction (for me, at least) and in IMC, and enclosed in active headsets, I could see where it could really be dangerous. I recently installed an AOA system and looking back, it was telling me the straight skinny, but as it is new to me, I hadn't learned to rely on or trust it as much as I should.
I suspected that , good for you!;)
 
Yea, I'm usually reluctant to post on the red board too, but in this case, I thought I'd risk it in the hopes that it might help someone else out. I'm fully prepared for the obligatory idiot label, and to be told what all I should have done to troubleshoot, etc., had I been anything other than a half-assed pilot :)

It was such a strange malfunction (for me, at least) and in IMC, and enclosed in active headsets, I could see where it could really be dangerous. I recently installed an AOA system and looking back, it was telling me the straight skinny, but as it is new to me, I hadn't learned to rely on or trust it as much as I should.

What kind of climb do you get out of your Cardinal? Looking at them as replacement for my Warrior II.
 
What kind of climb do you get out of your Cardinal? Looking at them as replacement for my Warrior II.

I usually fly at 1900-2200 pounds (gross is 2500) and from my airport at 700', I usually see 900'-1100' climbs at Vy, and that's in line with book values. But the other day with the temperature in the low twenties, it climbed at an estimated 1200-1300' (clean, and at a few mph faster than Vy).

The Warrior (a 1984 model) was the most recent aircraft I had been flying (logged ~50 hours) before I bought my Cardinal. My 177B will cruise at 119 knots true using 8.4 gph at ~5000' (65%). The big thing I like about the Cardinal is the easy ingress/egress (two doors) and the roominess. Both have big stabs and I found the Warrior easy to land, and once I got the hang of the Cardinal, it is just as easy. Stalls are similarly benign on both. I really enjoyed flying a low wing and did not want to give up the pattern visibility (being able to see the runway while on base), and the Cardinal, with its rearward wing, is about the only high wing that will allow that.

It has great visibility with the high, strut-less wing, and it is easy to get in and out of and roomy. This is where the Cardinal really shines. But if you're looking for a significant speed/climb increase and don't mind a single door, there are lots of other options out there. Why are you looking to replace your Warrior?
 
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. Why are you looking to replace your Warrior?

For the very reasons you cited as positives of the Cardinal: 1)Ingress/egress comfort of two doors and above average cabin width and 2)better climb rate.

I priced the option of upgrading the Warrior to an O-360, or selling the warrior and getting an archer, and it simply didn't seem like a value swap to me, to end up with one door anyways. I really have grown to hate the right door ingress; my C-150 was more friendly to get in and out of to be honest. If I hit my knee with the throttle quadrant one more time I'm gonna lose my mind LOL.

I'm a little gunshy about the B model Cardinal engine due to the crankshaft AD affecting the -A1F6 and F6D engines, but there might be some great value in the fixed pitch A models or 180HP '68 conversions. Like you, my passenger mission set could be accomplished under 2350MGW, which I hear is still a legal limitation of the '68 models even with the engine upgrade (stupid legal CYA....)

I get 500-650fpm on cold day in TX with a passenger and full fuel on the warrior II, even less than that in the summer. My mission will be 90% sub-300NM with the option of going on destinations 300NM and 450NM away. Have done the latter with one passenger with the Warrior, so I suspect the cabin of the Cardinal (bigger than a 182!) would make it much more comfortable a trip from initial ingress to destination egress.
 
Don't forget another difference between a 177 and the other planes you are comparing, the 177 handles control input wise like a sport bike or porsch whereas a 182 handles more like a minivan for feel. The visabiliy is impressive also sitting essential under the leading edge.

For the very reasons you cited as positives of the Cardinal: 1)Ingress/egress comfort of two doors and above average cabin width and 2)better climb rate.

I priced the option of upgrading the Warrior to an O-360, or selling the warrior and getting an archer, and it simply didn't seem like a value swap to me, to end up with one door anyways. I really have grown to hate the right door ingress; my C-150 was more friendly to get in and out of to be honest. If I hit my knee with the throttle quadrant one more time I'm gonna lose my mind LOL.

I'm a little gunshy about the B model Cardinal engine due to the crankshaft AD affecting the -A1F6 and F6D engines, but there might be some great value in the fixed pitch A models or 180HP '68 conversions. Like you, my passenger mission set could be accomplished under 2350MGW, which I hear is still a legal limitation of the '68 models even with the engine upgrade (stupid legal CYA....)

I get 500-650fpm on cold day in TX with a passenger and full fuel on the warrior II, even less than that in the summer. My mission will be 90% sub-300NM with the option of going on destinations 300NM and 450NM away. Have done the latter with one passenger with the Warrior, so I suspect the cabin of the Cardinal (bigger than a 182!) would make it much more comfortable a trip from initial ingress to destination egress.
 
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