Black Smoke in my Rocket

[Captain Bash]

Its annual time.

I was planning on a quick 30 minute flight to warm her up for the oil change. On downwind I was advised by unicom that I was trailing black smoke.

No oil was lost, still had 11qts after landing. 

I did notice that my fuel flow on takeoff was rather high. 40GPH. Isnt the TSIO-520NB supposed to be at 33GPH at full throttle?

Thoughts?

[Captain Bash]

Also, everything was in the green. 

Cht all below 340

TiT 1400

Oil temp 175

Plenty of manifold pressure. 

Edited February 13, 2020 by Captain Bash

[Yetti]

https://blog.firestonecompleteautocare.com/maintenance/what-is-my-exhaust-color-telling-me/

[Captain Bash]

Shout out to M20Doc!

Found this in a reply to a thread about starting issues with an 20k.

https://www.google.com/url?sa=t&source=web&rct=j&url=https://www.twincessna.org/pdf/SID97-3G.pdf&ved=2ahUKEwihg-bysM_nAhVPuZ4KHe6nB5AQFjAAegQIBRAC&usg=AOvVaw3-IMH__Wwc8PVR4eQBbn99

[carusoam]

C B,

How did your FF get changed to be so high?

Best regards,

-a-

[Captain Bash]

1 minute ago, carusoam said:

C B,

How did your FF get changed to be so high?

Best regards,

-a-

My IA said he spoke with the technicians at Continental.

He was told that there are diaphrams in the engine that can slowly slip out of its "adjustment" over time. The SB that is mentioned earlier is actually part of the official maintenance manual now and must be checked every annual.

I don't know the exact wording of it. I'll talk to him either tomorrow or Monday and post an more detailed update in here when I do.

 

[carusoam]

Part of my T/O procedure is a quick glance at MP and FF...

I never expected that too high could be a possibility...
 

Running too rich On T/O can be a real hazard on a short field  or obstructed climb out...

Thanks for sharing the details...

Best regards,

-a-

[Captain Bash]

Yeah, I've never see.n it so high. Something has failed, and reading this one article, it seems it could be many things. 

https://www.aopa.org/news-and-media/all-news/2015/april/22/repair-tips-for-failed-fuel-injection-system-components

[Austintatious]

8 hours ago, Captain Bash said:

My IA said he spoke with the technicians at Continental.

He was told that there are diaphrams in the engine that can slowly slip out of its "adjustment" over time. The SB that is mentioned earlier is actually part of the official maintenance manual now and must be checked every annual.

I don't know the exact wording of it. I'll talk to him either tomorrow or Monday and post an more detailed update in here when I do.

 

Ok, as someone who has been going round and round with fuel flow.... This makes no sense to me... The only way those diaphragms are going to drift is if the lock nut comes loose.

You have several adjustments to the fuel system... Full throttle metered pressure, idle pressure, idle mixture, low idle stop and 1 other adjustment on the fuel pressure regulator.

The ones in bold are the diaphragms.  They are on the rear of the engine.  A pain to get to, but a simple adjustment with one bolt and a LOCK nut to set them in place... dont see how they can move.

[carusoam]

Let’s see if @M20Doc can add some clarity to the FF settings on a continental / Rocket engine...

Best regards,

-a-

[Guest]

To have such a large shift in take off fuel flow most likely something has failed, seldom do adjustments change on their own in such a big way.

The same installation in a Cessna twin uses an external fuel pressure regulator to control fuel flow at maximum power, when power is reduced to climb power the pressure is controlled by the aneroid on the pump.  I don’t know if the Rocket installation uses this regulator?

I would have your maintainer check the fuel system pressures per the manual and the settings required per the STC.  
 

Clarence

 

[aviatoreb]

I can't imagine how that slipped so much.  Did you happen to notice the FF on recent take-offs?  Was it near 33 recently and then slipped suddenly to 40 or has it been a gradual slip?

I had my fuel servo replaced about 3 years ago due to a tiny leak but that leak was found on cowl off run up during annual and did not show itself from the pilots seat or engine monitors in flight operations.

Anyway, now that you are safe on the ground - this is nothing a credit card can't fix.

[Captain Bash]

Well, just got off the phone with my IA.

The MO for the engine recommends an overhaul of the fuel system every 10-12 years. Seeing as the engine was installed in and hasn't had the service in the past, it's way past due lol. 

So the entire fuel system is being removed and sent to a continental shop for overhaul. The also set all the parameters at that time. Mixture the whole 9 yards.

$3000 and 4 week turnaround but hey, airplanes right? 

Edited February 17, 2020 by Captain Bash

[FloridaMan]

I have to use the low boost pump as soon as I hit around 17,000ft in the climb or my fuel flow drops off; once I level off, I can turn the pump off and all is well.