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The Unexpected Drop of MP at 12K Ft

Re: The Unexpected Drop of MP at 12K Ft

painlesspotter said:
Alex
My wife, over 4 decades, uses rosarie beads and has worn out a few sets. She is always ready. It is just the price of going shopping in exotic places.
John P.
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I can appreciate that. It's hard to tell yet, but I am hoping she will eventually be ok to get on again.

From my end. I called my instructor and told him when the plane gets back we are going up to practice as many emergencies we can think of.
 
Re: The Unexpected Drop of MP at 12K Ft

Hey Alex,

Great write up! Sounds like you kept your cool and demonstrated exceptional decision making skills.
 
Re: The Unexpected Drop of MP at 12K Ft

Several years ago, as I advanced the throttle for takeoff, the MP pressure rose to 32", and No more. I advanced the throttle to the stops and 32 was all I got. The aircraft was accelerating, but not very quickly. I figured the turbo was out of the picture, as I only got 32 inches. Turns out a cable problem. Point being, the engine will run if the turbo wheel can spin, and you will get normal MP for the altitude you're at, but with the TO-360, you won't get a lot of HP. At light weight, I'm confident one could maintain level Flight at lower altitudes, but not sure what would happen at high weights.
 
Re: The Unexpected Drop of MP at 12K Ft

plight said:
Hey Alex,

Great write up! Sounds like you kept your cool and demonstrated exceptional decision making skills.
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The day after is when it starts to set in. I frankly feel humbled and greatful.

Very happy to see so many good thoughts exchanged by so many smart and experienced people on this board. The opportunity to learn from each other is priceless and helps us all stay safe doing what we all love.

Looking forward to flying again soon.
 
Re: The Unexpected Drop of MP at 12K Ft

Alex,

I totaly get it. In my old 112TCA, I had an exhaust valve stick open in flight. Needless to say, not a lot of fun.
 
Re: The Unexpected Drop of MP at 12K Ft

jrichards said:
Hi Alex,

Good work!

For those who may set the glide distance in their EFB's, etc, please fly some glides first so you know what YOU can reliably achieve. The book is optimistic on this, as usual.

Jim
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Interestingly enough there's an article in AOPA magazine this month that says, in order to get your POH glide ratio, that you must retard the prop to min RPM! I had never heard that before but as a guy with 4,000+ jet hours and only around 300 in pistons I found that very informative!

Mike
 
Re: The Unexpected Drop of MP at 12K Ft

alexnor said:
I can't imagine this scenario with a panic on the right seat. Its a good wife conversation to have in the comfort of one's home to get them in the mind set for when an emergency happens. I am glad we had it at a while back and she followed through.
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I've got a good one, though she normally limits her flights for Fly-ins or Grandkid runs. Last month we lost the alternator IFR inside Atlanta's Class B. Took a few mins to realize followed by losing comm's then the Aspen which drives the autopilot. Hand flying in the soup off of backup Inst's she calmly asked, 'we going to be all right?" Was able to isolate a heavy amp draw off of recent air cond project and regain all in a few min's. She never freaked out during it all. . .
 
Re: The Unexpected Drop of MP at 12K Ft

I have actually had a turbo cable break on TO. It is squirrely but controllable with throttle. Here's something not mentioned that you should do at a minimum of every annual (maintenance manual says 50 hrs.) Disconnect the throttle turbo cable from the wastegate and make sure you it moves freely and returns to the stop. The exhaust flow with increased throttle will override the tension of the return spring. You can actually overboost if you don't get the hang of it quickly. I suspect in Alex's case, since he didn't get the throttle response, that his wastegate is stuck or binding. Like Joel noted, you don't want to put any lubricant on the turbo system. I myself don't like using mouse milk either.

Commander91gm said:
In a failure such as this the wastgate defaults to open which sends most of the exhaust gas down the tailpipe. The loss of a portion of the exhaust gas to the turbo, and the reduction in rpm's of the turbo is what accounts for the power loss.

Inspection of the wastegate, turbo, cable and rod ends should be regularly done. I do so at each oil change (takes a few minutes.)
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Re: The Unexpected Drop of MP at 12K Ft

Planecents said:
I have actually had a turbo cable break on TO. It is squirrely but controllable with throttle. Here's something not mentioned that you should do at a minimum of every annual (maintenance manual says 50 hrs.) Disconnect the throttle turbo cable from the wastegate and make sure you it moves freely and returns to the stop. The exhaust flow with increased throttle will override the tension of the return spring. You can actually overboost if you don't get the hang of it quickly. I suspect in Alex's case, since he didn't get the throttle response, that his wastegate is stuck or binding. Like Joel noted, you don't want to put any lubricant on the turbo system. I myself don't like using mouse milk either.
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I will definitely look at this closely when I get back to the airplane.

If its binding what would you use if not lubricant nor mouse milk?
 
Re: The Unexpected Drop of MP at 12K Ft

If its binding it is time for replacement - no good lubricants available.


As said earlier they need to be run dry!
 
Re: The Unexpected Drop of MP at 12K Ft

x2. No lubricant there. Ever.

Unfortunately the A&Ps will always get you.
They will assign the task to the apprentice - who will "help" by putting lube in there.

You can't babysit the annual enough ..
 
Re: The Unexpected Drop of MP at 12K Ft

On that note - is it possible to "unlube it" ? I always find myself in this predicament. No matter how hard I try - I end up with lube on it sooner or later.

I just replaced mine this annual (a couple of weeks ago - it was time.

I am headed back into shop to address a rigging issue.

Throttle is too springy on the low end when cold. Minimum 1200 RPM on idle unless I hold it down to the stops. If I let go, it jumps back to 1200 RPM. Seems like a rigging issue.
I'll check for lube as well on the waste gate end ..
 
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Re: The Unexpected Drop of MP at 12K Ft

alim said:
On that note - is it possible to "unlube it" ? I always find myself in this predicament. No matter how hard I try - I end up with lube on it sooner or later.

I just replaced mine this annual (a couple of weeks ago - it was time.

I am headed back into shop to address a rigging issue.

Throttle is too springy on the low end when cold. Minimum 1200 RPM on idle unless I hold it down to the stops. If I let go, it jumps back to 1200 RPM. Seems like a rigging issue.
I'll check for lube as well on the waste gate end ..
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I believe Frank at Beechhurst recommends soaking it in Jet fuel to get any lubricants out.
The fuel should evaporate out.
 
Re: The Unexpected Drop of MP at 12K Ft

Brake clean, or similar, will "un-lube" it.
 
Re: The Unexpected Drop of MP at 12K Ft

So... reading over all of these posts, here is what I took away:
1. Inspect the wastegate cable at least every 50 hours (or every oil change)

2. NEVER lubricate the wastegate cable
3. Practice flying the plane at 20" of MP


Anything I missed?
 
Re: The Unexpected Drop of MP at 12K Ft

Craig said:
So... reading over all of these posts, here is what I took away:
1. Inspect the wastegate cable at least every 50 hours (or every oil change)

2. NEVER lubricate the wastegate cable
3. Practice flying the plane at 20" of MP


Anything I missed?
Click to expand...


You got it!


First indication of problems with the cable will be stiff throttle movement.
 
Re: The Unexpected Drop of MP at 12K Ft

Great job flying the airplane Alex!! Glad you and wife are ok..
 
Re: The Unexpected Drop of MP at 12K Ft

Commander91gm said:
First indication of problems with the cable will be stiff throttle movement.
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Would that include on the ground, with the engine shut off?
 
Re: The Unexpected Drop of MP at 12K Ft

I just resolved an issue.
My cable and rod ends were finally showing signs of binding.
Symptoms :After an hour of flight, throttle got stiff. Loose when cold - there is a parallel thread on the issue. I will post update there as well.
Instead of piecemeal - I replaced both the “transition cable” and rod ends at the turbo. Certainly the rod end hadn’t been replaced in 18 yrs so I figured it’s time.

Back to your question : after replacement - when cold - there was new low end stiffness. But not the symptoms I had when hot during flight (usually observable on a go around when u ask for power back. New symptom - springy cable with stiffnes. This was a cable routing issue. We just solved it yesterday. Now there is minor stiffness but that appears to be the butterfly valve in the turbo. I will address at next annual.

I just flew back (last night ) from Mech to homebase. No more heat stiffness or routing stiffness observed.

My experience anyway.
 
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