NTSB Issued Final Report for the 2019 Acclaim Ultra down at DVT

[mike_elliott]

Don,

Mark was fully briefed by Kevin K Mark W and Dan on the use of the low boost pump during his factory transition training. The entire FITS based scenario training standards were satisfactorily completed by Mark. This doesnt say vapor lock didnt come into play, but coming from someone who has done 90% of the new Ultra Acclaim transitions, rest assured he was properly instructed. Please dont infer he wasnt properly trained here unless you know he wasnt. The lawyers will be swimming all over this as it is. As you know, I personally did not do Marks training as I was doing another Ultra Acclaim at that time, but did debrief everyone.

Mike Elliott

Mooney Pros, Inc.

MCFI

FAASTEAM Lead Rep.

[donkaye, MCFI]

4 hours ago, mike_elliott said:

Don,

Mark was fully briefed by Kevin K Mark W and Dan on the use of the low boost pump during his factory transition training. The entire FITS based scenario training standards were satisfactorily completed by Mark. This doesnt say vapor lock didnt come into play, but coming from someone who has done 90% of the new Ultra Acclaim transitions, rest assured he was properly instructed. Please dont infer he wasnt properly trained here unless you know he wasnt. The lawyers will be swimming all over this as it is. As you know, I personally did not do Marks training as I was doing another Ultra Acclaim at that time, but did debrief everyone.

Mike Elliott

Mooney Pros, Inc.

MCFI

FAASTEAM Lead Rep.

Where does this post come from?  I said I had my suspicions, but wasn't accusing anyone of anything.  While I'm sure Continental has their reasons for having return lines going back to their respect tanks and not just on Mooneys, I think they are more prone to vapor lock than the Lycoming engine which doesn't have the return lines.  So, while I would and have taken off in my plane in above 100°F temperatures, I personally am uncomfortable doing so with the Continental Engine, thus staying overnight in Scottsdale on my last transition training.  Maybe that wasn't necessary, but it made me feel better anyway.

[Schllc]

As many times I have read this page in both the acclaim and the ovation poh’s, I never read these as compulsory because of the “or”.  
I also never had any Mooney specific instruction until I went to my first ppp which was years after I had my first Mooney  

Never once in 1,000 hours have I run the low boost pump in the climb. I was also completely unaware of any issues regarding this being a “known” issue with the continental 550 series. 
For all of the acclaims and ovations I have flown, when the low boost pump is engaged, the fuel flow usually drops which is counterintuitive for a turbo engine in the climb, which is another reason I never used the pump in the climb. 
I also fly in pretty hot temperatures regularly in the south from Florida to Texas, and have never had anything resembling vapor lock, so this is very intriguing to me. 
Does anyone have any documentation about this issue and why it’s unique to these engines?  Are the 550’s the only engines with return lines?
 

[Fly Boomer]

3 minutes ago, Schllc said:

Are the 550’s the on,y engines with return lines?

I think all the Continental's used in Mooneys have them.

[Danb]

2 hours ago, Schllc said:

As many times I have read this page in both the acclaim and the ovation poh’s, I never read these as compulsory because of the “or”.  
I also never had any Mooney specific instruction until I went to my first ppp which was years after I had my first Mooney  

Never once in 1,000 hours have I run the low boost pump in the climb. I was also completely unaware of any issues regarding this being a “known” issue with the continental 550 series. 
For all of the acclaims and ovations I have flown, when the low boost pump is engaged, the fuel flow usually drops which is counterintuitive for a turbo engine in the climb, which is another reason I never used the pump in the climb. 
I also fly in pretty hot temperatures regularly in the south from Florida to Texas, and have never had anything resembling vapor lock, so this is very intriguing to me. 
Does anyone have any documentation about this issue and why it’s unique to these engines?  Are the 550’s the only engines with return lines?
 

Dan being a long time Mooney pilot but very short time Acclaim pilot this has be completely confused due to the ambiguity or my stupidity 

[Schllc]

If I understand correctly, from what Don and Mike are saying, is that in the acclaim, the poh states that the low boost must be on during the climb, as well as anytime you are above 18,000. 
Come to think of it, the turbo cirrus has the same engine, and this procedure was never mentioned in my checkout in that plane either. 

Edit for clarification, climb over 12k low boost pump on, not entire climb. 
 

[DCarlton]

Coke vs Pepsi, Chevy vs Ford, Continental vs Lycoming... I guess I stay in the Lycoming camp.  If only there were an IO-540 powered Mooney.  

Edited August 26, 2023 by DCarlton

[Danb]

[exM20K]

1 hour ago, Schllc said:

If I understand correctly, from what Don and Mike are saying, is that in the acclaim, the poh states that the low boost must be on during the climb, as well as anytime you are above 18,000.

Climb over 12,000 feet is what the POH calls for.  I do this and have had no issues.  I also observe a drop in FF when engaging the pump to switch tanks, but I believe this doesn’t happen in a full power climb.  I’ll look next time.

it is hard for me to believe that a 10* difference in ground temperature would change anything in a system that is running probably 150*+ induction air.  
 

fuel system setup is very important in these planes and best done with two people: 1 looking at the pressure gauges and one in the cockpit  running the engine, which will get high CHTs very quickly.  When mine was set incorrectly, I’d get an over-rich stumble at the top of climb and 36+ GPH.  Or, it would not idle well and was always on the cusp of shutting off.  Now, it runs like a Singer sewing machine.

-dan

[exM20K]

Great news: it appears on one page back in this thread that a well-regarded and recently disengaged member’s posts live on, only not with his name attached. So the tread continuity is intact.

-dan

[Schllc]

2 hours ago, exM20K said:

Climb over 12,000 feet is what the POH calls for.  I do this and have had no issues.  I also observe a drop in FF when engaging the pump to switch tanks, but I believe this doesn’t happen in a full power climb.  I’ll look next time.

it is hard for me to believe that a 10* difference in ground temperature would change anything in a system that is running probably 150*+ induction air.  
 

fuel system setup is very important in these planes and best done with two people: 1 looking at the pressure gauges and one in the cockpit  running the engine, which will get high CHTs very quickly.  When mine was set incorrectly, I’d get an over-rich stumble at the top of climb and 36+ GPH.  Or, it would not idle well and was always on the cusp of shutting off.  Now, it runs like a Singer sewing machine.

-dan

Thanks for clarifying, 100% on the fuel setup. Most I’ve experienced either didn’t take the time to do it correctly or can’t. But when it’s correct it runs very well in all phases. 
(As long as timing is correct and bonus if you have fine wires plugs).

[kortopates]

If I understand correctly, from what Don and Mike are saying, is that in the acclaim, the poh states that the low boost must be on during the climb, as well as anytime you are above 18,000. 
Come to think of it, the turbo cirrus has the same engine, and this procedure was never mentioned in my checkout in that plane either. 

Edit for clarification, climb over 12k low boost pump on, not entire climb. 
 

I see vapor lock issues at least every other week with my Savvy work. It doesn't usually bring down planes, but it often causes a pilot to abort the climb and return to base due to a partial power loss.
I am sure you've just forgotten the Cirrus POH procedures since they're much bigger on the boost pump than Mooney's POH's 
But for sure, the IO-550's and especially the turbo 550's which are more prone to vapor lock issues are used by 3 airframe manufacturers (Mooney's, Cirrus and Cessna's). Yet I think I see fewer issues with the Cirrus pilots because ALL 3 Cirrus POH's (NA, TAT and TSIO-550) all say to use the Boost pump in climb and then to leave it on for 30 min after reaching cruise, or keep on above 18K. Whereas Mooney and Cessna say to turn on above 9 or 12K (DA). But of course pilots forget to use the boost in climb and or aren't thinking DA either and delay.
The Cirrus fuel set up is even done with the fuel boost pump ON since they recommend turning it on throughout the entire climb.
I don't believe its ground temp so much that leads to it, but higher CHTs absolutely helps induce it from the added heat radiating to the fuel injector lines. But we still see it in summer even without hot CHTs so its not the only factor.

[hubcap]

Myrtle has the Continental TSIO-360-LB. I just checked my POH and it clearly states that if there is fluctuating fuel flow during high ambient temperature operations, you are to turn on Low Boost and monitor fuel flow. 
 

I did not know that. Thank you.

[skykrawler]

16 hours ago, hubcap said:

Myrtle has the Continental TSIO-360-LB. I just checked my POH and it clearly states that if there is fluctuating fuel flow during high ambient temperature operations, you are to turn on Low Boost and monitor fuel flow. 
 

I did not know that. Thank you.

Turbo Arrows (similar engine) also have the 'vapor suppression' instructions.

Isn't vapor lock a problem with drawing fuel UP from the tank?  That is...the intake side of the pump has negative pressure.     Thus, the boost pump to reduce or eliminate the lower pressure and the tendancy for the fuel to vaporize.

A tank venting problem can cause vapor lock, no?

[kortopates]

12 minutes ago, skykrawler said:

Turbo Arrows (similar engine) also have the 'vapor suppression' instructions.

Isn't vapor lock a problem with drawing fuel UP from the tank?  That is...the intake side of the pump has negative pressure.     Thus, the boost pump to reduce or eliminate the lower pressure and the tendancy for the fuel to vaporize.

A tank venting problem can cause vapor lock, no?

True, the high wing Cessna's really don't have this issue. As an example, the late 70's era of C210 POH's don't even mention need for vapor suppression with use of boost pump. It is a low wing issue for the reasons you stated. But in my opinion not enough pilots take the threat seriously.

For every low wing continental powered aircraft with over 200+HP, except for starting, priming, switching tanks, the low boost pump is for vapor suppression while the high boost pump is for a engine driven pump failure.

 

[EricJ]

1 hour ago, skykrawler said:

Isn't vapor lock a problem with drawing fuel UP from the tank?  That is...the intake side of the pump has negative pressure.     Thus, the boost pump to reduce or eliminate the lower pressure and the tendancy for the fuel to vaporize.

Yes, the pump increases the line pressure downstream so that it stays above the vapor pressure of the fuel at the input to the mechanical pump.    This can help prevent cavitation or boiling (vapor lock) in the line between the boost pump and the mechanical pump.

[Schllc]

Three hour plus fights since this topic mentioned the low boost. 
My fuel flow reduces by almost 1.5 gph with the low boost pump on during cruise. Egt spikes and tit increases.  I cannot use the low boost in the climb because the fuel flow drops below 30gph  

is this normal or does the low boost pump flow need to be adjusted?