BeechTalk - BT

Username Protected · **Posted:** 05 Aug 2025, 17:11

does JPI measure fuel flow? Too much and it'll stumble...

what was OAT? I assume at SL not over 100 df, unlikely to be vapor lock but you never know.

I've been taught when dealing with engine problems everything goes forward:
mixture, prop, throttle (scroll in), boost pump on (switch forward), etc etc.

not a great feeling when you don't know why. good luck!

Username Protected · **Posted:** 05 Aug 2025, 17:31

Thanks for your comments Joel..
It was about 75°smooth, near sea level and the JPI does have FF and other than when I pushed the mixture in, it was almost impossible to see data at the event point. Even though was using 1 sec. Sample rate...
Yep!
Another plane mystery however with the help of brand x owners on the forum I am realizing that this is far from an unheard of issue.
Everyone seems to ID it as a fuel issue and turns on a pump or switches tanks and that cures it.

The one comment about describing it as a sudden mixture pull and push is exactly how I described it.
So I will investigate and fly and report back to the forum.
Thx again,
Eliot

Username Protected · **Posted:** 05 Aug 2025, 18:18

Username Protected wrote:

Another plane mystery however with the help of brand x owners on the forum I am realizing that this is far from an unheard of issue.
Everyone seems to ID it as a fuel issue and turns on a pump or switches tanks and that cures it.Eliot

Eliot, I think you have nailed it with your research. What you experienced is far from uncommon - you just need the right set of conditions to experience that pause which gets your attention right quick! My understanding is that all blends of 100LL are not exactly the same so that might be a contributing factor as well.

Username Protected · **Posted:** 05 Aug 2025, 18:34

Good heads up.
Thx
Safe skys

Username Protected · **Posted:** 05 Aug 2025, 19:11

Username Protected wrote:

Thx Sven.
The Columbia has an arm feature on the boost pump that turns it on automatically with loss of FP. So no low boost is used for all normal ops.
Also, I've been flying this plane and engine for 500hrs over 8 years and it has never done this before. The engine pump has never needed supplementation.
Something has changed.
The Columbia and probably all Beech products have some kind of slosh box for immediate fuel supply feed so the pickup is never uncovered due to fuel moving around the tank.
The entry of fuel into that box has a flapper door that if blocked could easily cause fuel starvation for any length of time.
This is just a logical theory based on the design of the tank. Do you know if there is a similar design in Barons?

Is the "slosh box" common or does each side have one in the wing root?

Username Protected · **Posted:** 05 Aug 2025, 19:30

Username Protected wrote:

Thx Sven.
The Columbia has an arm feature on the boost pump that turns it on automatically with loss of FP. So no low boost is used for all normal ops.
Also, I've been flying this plane and engine for 500hrs over 8 years and it has never done this before. The engine pump has never needed supplementation.
Something has changed.
The Columbia and probably all Beech products have some kind of slosh box for immediate fuel supply feed so the pickup is never uncovered due to fuel moving around the tank.
The entry of fuel into that box has a flapper door that if blocked could easily cause fuel starvation for any length of time.
This is just a logical theory based on the design of the tank. Do you know if there is a similar design in Barons?

Is the "slosh box" common or does each side have one in the wing root?

Username Protected · **Posted:** 05 Aug 2025, 19:46

Username Protected wrote:

Later style Bonanza and Baron main fuel tanks have internal baffling to prevent unporting. There is nothing external to the fuel cell.

In the Columbia?

Username Protected · **Posted:** 06 Aug 2025, 08:37

Thanks Sven.

Username Protected · **Posted:** 06 Aug 2025, 09:24

Username Protected wrote:

Thx Sven.
The Columbia has an arm feature on the boost pump that turns it on automatically with loss of FP. So no low boost is used for all normal ops.
Also, I've been flying this plane and engine for 500hrs over 8 years and it has never done this before. The engine pump has never needed supplementation.
Something has changed.
The Columbia and probably all Beech products have some kind of slosh box for immediate fuel supply feed so the pickup is never uncovered due to fuel moving around the tank.
The entry of fuel into that box has a flapper door that if blocked could easily cause fuel starvation for any length of time.
This is just a logical theory based on the design of the tank. Do you know if there is a similar design in Barons?

My Malibu started going crazy on EGTs on climb out one hot day. Low boost stopped all the nonsense. Only happened once in 8 years of ownership.

Username Protected · **Posted:** 07 Aug 2025, 09:52

Yep!
That would give you a couple of gph higher in addition to any other advantages. Same in Columbias on hot days...
Thx!

Username Protected · **Posted:** 09 Aug 2025, 23:47

Username Protected wrote:

I was just trying to zero in on what large time frame it occured and how much time in months or weeks it has had since then to recur.
Min happened about 3 weeks ago, was only 3-5 seconds long and I flew an hour and a half after that and then 2 local test flights after that with no recurrence.
Thx

It was a flying club airplane, so it had plenty of opportunity to repeat, but I would not necessarily have heard about it. There was some speculation among my coworkers that it might have been vapor from the fuel return line that filled the small header tank, blocking normal flow.

Username Protected · **Posted:** 09 Aug 2025, 23:48

Username Protected wrote:

I was just trying to zero in on what large time frame it occured and how much time in months or weeks it has had since then to recur.
Min happened about 3 weeks ago, was only 3-5 seconds long and I flew an hour and a half after that and then 2 local test flights after that with no recurrence.
Thx

It was a flying club airplane, so it had plenty of opportunity to repeat, but I would not necessarily have heard about it. There was some speculation among my coworkers that it might have been vapor from the fuel return line that filled the small header tank, blocking normal flow.

Username Protected · **Posted:** 10 Aug 2025, 10:48

Ok. Thanks for the reply.
I have now attempted to recreate the exact conditions on 5 separate flights and the engine runs perfectly in all regards.
Even slips and skids during climb to uncover pickup, high FF to empty slosh box at at higher rate than it could gravity fill itself if it had a restriction.
Can do no more.
Obviously this is something that occurs occasionally in the industry.
I now know that thanks to the folks that have shared on this blog.

We will see what happens.
Regards,
Eliot

Username Protected · **Posted:** 30 Aug 2025, 00:31

Username Protected wrote:

I had this happen one time in a T210; running really rough and I thought it was going to quit.

I switched tanks, hit the boost pump and richened the mixture. Problem went away and never repeated itself.

Edit to add: There was some speculation that it might have been fuel vaporization where the vapor filled the small header tanks.

Username Protected · **Posted:** 30 Aug 2025, 11:33

Thanks Bill.
My mech says that is not an uncommon report for 210s.
An engine guru friend says same as you with an A36 IO-520....happened once and never again for 10 years.

We probably all just have to live with this potential remaining very sharp on immediate action memory items for engine failure after takeoff which we should anyway.

Even very well known GA maintenance sources acknowledge this effect.

Thanks for the response.
Will let you know if anything else comes up on the subject.
Regards,
Eliot

Engine hesitation in flight..