Engine stumbled two back to back flights

[Pinecone]

1 hour ago, 201Mooniac said:

Seems to be the consensus on many of the auto type forums.  I'm told it is due to the fuel helping to cool the pump but haven't verified if this is really true or an owt.

We did a straw poll on one of the BMW forums about fuel pump failures.   Almost every person who had one fail, ran their cars to the low fuel light before filling.  Almost no one who filled at 1/4 tank had a fuel pump failure.

It was dramatic

[Pinecone]

1 hour ago, PBones said:

I completely understand the calculations and planning and see that you are highly qualified, Thanks. I am new to this and have been studying intensely and the reason I am reading as many posts as I can. I still don't understand purposely running out a tank while the engine is running.

For me, and this is just me,  I will never "plan" to be that low on fuel at any point when flying because calculating fuel use is one thing, what can actually happen is another. I would rather make a stop than to risk my engine stalling and not restarting for some reason or doing damage to the engine by running out of fuel in one tank.

Very good.

You shouldn't PLAN to be that close on fuel.  But say you head out and have an hour extra fuel.  But you get to your destination and the runway is closed due a gear up.  You buzz around for 15 - 20 minutes and decide to divert. You fly 20 minutes to the nearest field.  So now you are about 5 gallons.  You REALLY want that 5 gallons in the same tank.  Otherwise you could be on final and someone pulls out on the runway and you have to go around.  And THEN you run a tank dry.

[PBones]

10 minutes ago, Pinecone said:

Very good.

You shouldn't PLAN to be that close on fuel.  But say you head out and have an hour extra fuel.  But you get to your destination and the runway is closed due a gear up.  You buzz around for 15 - 20 minutes and decide to divert. You fly 20 minutes to the nearest field.  So now you are about 5 gallons.  You REALLY want that 5 gallons in the same tank.  Otherwise you could be on final and someone pulls out on the runway and you have to go around.  And THEN you run a tank dry.

You are correct, that is why I like a lot of fuel! That should be the last thing to worry about. Not to worry, my wife can only go about 2.5 hours before she will force the plane down to the potty! So I will just fuel up while she powders her nose!

[EricJ]

1 hour ago, Pinecone said:

We did a straw poll on one of the BMW forums about fuel pump failures.   Almost every person who had one fail, ran their cars to the low fuel light before filling.  Almost no one who filled at 1/4 tank had a fuel pump failure.

It was dramatic

That used to be true in a lot of cars with submerged electric pumps.   They used the fuel for cooling, so the pump could potentially overheat if there wasn't sufficient fuel in the tank.   I think there may be other failure modes associated with repeatedly sucking air and having to reprime repeatedly, or that might have aggravated the overheating.   In any case, many race tanks have baffled sumps with check-valve type gates that keep the sump fuller than it would be otherwise, so the pump is less likely to pump air or overheat.

I don't think any Mooneys have pumps like that, though, or most GA airplanes.

[Hank]

3 hours ago, 0TreeLemur said:

Exactly.    WWII pilots routinely ran tanks dry.  Nothing quite as worthless as an unknown quantity of fuel sitting in the bottom of a tank when you are trying to get somewhere.   The POH for the older Mooneys more or less says: Take off and fly 1 hour on one tank, then empty the other tank, and land back on the tank you took off with.

Oh, you mean this gem:

It's in The Book, but I generally fly one hour each; on a long flight, one hour each, then 90 minutes or until I get nervous on the first tank (leaving it empty or very close), then switch to #2 and plan to land soon (I like to make this switch at or near the beginning of my descent to land).

But winds, weather and ATC will affect your flight time. I recently made 3 round-trips to Houston, 505 nm each way. Flight times averaged a bit over 3.5 hours, with a range of 3.0 to 4.5; the very slow one had variable headwinds and five (yes, 5!) reroutes, only two caused by MOAs going hot just before or just after i entered them.

1 hour ago, Pinecone said:

We did a straw poll on one of the BMW forums about fuel pump failures.   Almost every person who had one fail, ran their cars to the low fuel light before filling.  Almost no one who filled at 1/4 tank had a fuel pump failure.

Your car's fuel pump is in the tank and cooled by the fuel. The mechanical fuel pump is not inside the tank, it sits below it. Search for tank resealing photos, you'll see the flat bottom of the fuel tank, with a pickup sticking up ~1/4" off the bottom.

Then again, it may be just a BMW thing, I've got 161,000 miles on my Altima, and I generally fill up when the Range to Empty shows < 50 miles; it comes on anywhere from 72 - 108 miles to empty. My biggest problem is tires, I just replaced them for the third time, but this set cost the same as the last set (BF Goodrich Advantge+, P21560R16).

Probably need to replace the main gear tires on my Mooney soon (be warned--Michelin Airstop tubes are the best, you'll rarely need to add air except when temps cool off for winter, but they cost as much as the tires . . .) [Yep, airplane tires still have tubes, and they are purchased separately. ] I think I replaced my mains just before I moved back to Sweet Home in Feb '14, but it may have been a year before that; nose tires don't last as long, last changed mine Jan '17 or '18 (they last longer now that I'm based at a field with taxiway instead of backtaxiing and turning around on every takeoff and landing).

Happy flying!  

[PT20J]

Don’t forget that most autopilots have a limitation on the maximum fuel imbalance. It’s 15 gal. for my GFC 500.

[Pinecone]

On 8/21/2025 at 3:46 PM, PBones said:

You are correct, that is why I like a lot of fuel! That should be the last thing to worry about. Not to worry, my wife can only go about 2.5 hours before she will force the plane down to the potty! So I will just fuel up while she powders her nose!

https://www.amazon.com/s?k=traveljane&i=hpc&crid=2BLRGHVIT99LM&sprefix=traveljane%2Chpc%2C84&ref=nb_sb_noss_2

 

[MikeOH]

41 minutes ago, Pinecone said:

https://www.amazon.com/s?k=traveljane&i=hpc&crid=2BLRGHVIT99LM&sprefix=traveljane%2Chpc%2C84&ref=nb_sb_noss_2

 

Sure, if I want to lose half of everything in the ensuing divorce

[IvanP]

4 hours ago, Pinecone said:

https://www.amazon.com/s?k=traveljane&i=hpc&crid=2BLRGHVIT99LM&sprefix=traveljane%2Chpc%2C84&ref=nb_sb_noss_2

 

Not in my Mooney! There are some things that just should not be done in my plane unless it is an emergency and landing is not an option. I do carry couple of these in the plane for such occasions, but never had to actually use it. 

[Ragsf15e]

On 8/21/2025 at 12:46 PM, PBones said:

You are correct, that is why I like a lot of fuel! That should be the last thing to worry about. Not to worry, my wife can only go about 2.5 hours before she will force the plane down to the potty! So I will just fuel up while she powders her nose!

After I got my ppl (about 35 years ago, damn im old!) I thought the same way.  Why not top it off?  If landing with 1 hour is good, 2 is better for sure?  And sheesh, I need to stop anyway.  I think that’s a normal (and probably reasonable) way to start out.  When I went to USAF pilot training we always started with tanks full, but I quickly learned that to land with an hour of fuel, I’d have to fly a max of about 2 patterns and land.  Then, in the Eagle we would commonly land with about 2000lbs of fuel which sounds great, but then you realize that fuel burn on takeoff is in excess of 50,000 pph.  At normal settings, it’s 30 minutes or so. Sometimes not comfortable, but if you followed the rules about having an alternate and spoke up when you needed to divert or were minimum (or emergency) fuel, it works.  Why did we do it? Because otherwise you can’t get the utility out of the airplane.
 

 And Im not suggesting doing this in a Mooney either, but you trade utility (range and load) for fuel.  Now, as a corporate pilot, I do this every day.  It’s easy with foreflight because the planning profiles are accurate, the winds are accurate, and you can recalculate your plan as often as you like.  I commonly depart with half fuel in the Meridian so I can carry 3 or 4 pax instead of 2. I am also happy to tell my boss that I need more fuel if the winds or weather change and I drop a person off the trip to add gas.  I don’t get into regulatory minimum requirements with him, but I tell him I want a minimum of 1 hour fuel at landing (or alternate) and I stick to that.  
Now how about you and your wife in the Mooney? By all means, top it off every flight, but when the kids come, start looking at options.  I would fly my M20F 525nm to my folks with my wife, 2 kids and bags.  We generally landed with ~15gallons, but I couldn’t start full.  I would leave ~2 gallons in one tank and 13 in the other for landing.  Once I flew 600nm with them and I did run a tank dry to ensure I had everything in one tank.  Landed with ~12 gallons.  It’s a non event if you’re ready it barely stumbles.  My family was ready and were interested but not scared.  Ive also run a tank dry in my K to empty it and check fuel gage accuracy.  Now that I know how accurate the CIES gages are, I wont plan on it going completely dry in cruise but I can maximize remaining fuel in one tank and the utility of the airplane by getting within a couple minutes of dry on the low one.  And since Ive tested it in cruise, if I do it accidentally (I screw up), I know how it will restart.  To do this, you have to be willing and confident in checking your plan as you fly, ensuring that it works, and WILLING to divert if it’s not going to meet your personal mins.

Just last winter at Boeing Field in Seattle, I followed a citation down the ILS in a PA46T.  It was pretty foggy, but I thought we would see the lights. He went missed, and I was on the approach but much slower than him so I thought I still had a chance. I also went missed, but I did see the lights right as I started to add power. On the missed approach the citation asked to go back around and try it again since he had also seen the lights. I thought there was a reasonable chance that the fog was moving and he would land. Approach asked me what I wanted to do? I said I want to divert to the other side of the mountains and land in Wenatchee, which was VFR. He said do you want to try the approach again? I said no I want to divert immediately. And we went and landed comfortably with an hour of fuel still. You have to be willing to make that call.

[PBones]

6 hours ago, Pinecone said:

https://www.amazon.com/s?k=traveljane&i=hpc&crid=2BLRGHVIT99LM&sprefix=traveljane%2Chpc%2C84&ref=nb_sb_noss_2

 

Great Pinecone! But I believe MikeOh is correct, easier to fly a whole plane! Not sure if 1/2 a prop, one aileron and 1/2 an elevator will work well, not to mention the intense draft! 

[Hank]

14 minutes ago, PBones said:

Great Pinecone! But I believe MikeOh is correct, easier to fly a whole plane! Not sure if 1/2 a prop, one aileron and 1/2 an elevator will work well, not to mention the intense draft! 

Always remember, you can sleep in an airplane, but you can't fly a house!

[Pinecone]

My SO experimented with one at home.   While the look the same, the Travel Jane worked better (less chance of leakage.  But she found that one of the funnels was even better.  To be used with the Travel Jane as a receptical.

https://www.amazon.com/dp/B08T97KZDD?ref_=ppx_hzsearch_conn_dt_b_fed_asin_title_1&th=1

This is strictly for emergencies, but we typically fly 14,000 - 17,000, so it is a good 30 minutes to the ground, plus taxi to parking, etc.  So, if the need is really there ......

 

[IvanP]

5 minutes ago, Pinecone said:

My SO experimented with one at home.   While the look the same, the Travel Jane worked better (less chance of leakage.  But she found that one of the funnels was even better.  To be used with the Travel Jane as a receptical.

https://www.amazon.com/dp/B08T97KZDD?ref_=ppx_hzsearch_conn_dt_b_fed_asin_title_1&th=1

This is strictly for emergencies, but we typically fly 14,000 - 17,000, so it is a good 30 minutes to the ground, plus taxi to parking, etc.  So, if the need is really there ......

 

Amen to that. Emergency use only. I made a restroom visit part of passenger pre-boarding check list for my wife. Speedbrakes are awesome if you need to get down from 16k quickly. Had to do it not so long ago for a forced potty break.  

[201er]

2 hours ago, Pinecone said:

My SO experimented with one at home.   While the look the same, the Travel Jane worked better (less chance of leakage.  But she found that one of the funnels was even better.  To be used with the Travel Jane as a receptical.

https://www.amazon.com/dp/B08T97KZDD?ref_=ppx_hzsearch_conn_dt_b_fed_asin_title_1&th=1

This is strictly for emergencies, but we typically fly 14,000 - 17,000, so it is a good 30 minutes to the ground, plus taxi to parking, etc.  So, if the need is really there ......

 

Jose Monroy spoke rather fondly of his piss hose that poured out a venturi underneath the fuselage all over the underside of the plane. 

[Hank]

2 hours ago, IvanP said:

Amen to that. Emergency use only. I made a restroom visit part of passenger pre-boarding check list for my wife. Speedbrakes are awesome if you need to get down from 16k quickly. Had to do it not so long ago for a forced potty break.  

Throttle back, 45° bank, maintain cruise speed, you will fall out of the sky under control. It's one of my practiced emergency descent. Can't say how fast we came down, my IVSI was pegged.

[IvanP]

6 minutes ago, Hank said:

Throttle back, 45° bank, maintain cruise speed, you will fall out of the sky under control. It's one of my practiced emergency descent. Can't say how fast we came down, my IVSI was pegged.

Yes, that will work great. For potty break, I would choose a bit less agressive approach to avoid passenger discomfort (my wife does not enjoy steep spiral maneuver) - throttle back to about 18in MAP, pop brakes and point the nose down in the direction of the airport, descend at about 1,500 fpm or so, on the ground in about 10-15 min. 

[Pinecone]

11 hours ago, Hank said:

Throttle back, 45° bank, maintain cruise speed, you will fall out of the sky under control. It's one of my practiced emergency descent. Can't say how fast we came down, my IVSI was pegged.

And how were everyone's ears?

[Hank]

4 hours ago, Pinecone said:

And how were everyone's ears?

Just fine. If a yawn won't clear yours, visit your nearby ENT doctor.

[Pinecone]

I am fine, but pax may not be with excessive descent rates.

[Hank]

2 hours ago, Pinecone said:

I am fine, but pax may not be with excessive descent rates.

Depends how badly your pax want to be on the ground . . .