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  #1  
Old 04-25-2020, 04:12 PM
Tankerpilot75's Avatar
Tankerpilot75 Tankerpilot75 is offline
 
Join Date: Jan 2015
Location: Oklahoma City, OK
Posts: 683
Default Has anyone else experienced this?

Finishing up my annual condition inspection and the A&P and I were checking connections and nuts on FWF. Everything was tight and secure except when we got to the fuel injector throttle body. Only one of the four nuts securing it to the engine was tight. Two were so loose you could spin them with your fingers and one was totally gone. The engine still ran smoothly.

Replaced all star lock washers, replaced the missing nut and tightened all to torque. We then added four nylon end nuts on top of the existing nuts and secured them - there was just enough room on the studs.

My A&P said this was the first time he?s ever seen nuts loosened like this - especially if no one?s worked on the item. He distinctly remembers checking the throttle body last year and every thing appeared secure then.

Our question: My engine is the Superior XP IO-360 B1AA2, has anyone else found they?ve had to tighten these nuts due to them becoming loose? This could have really ruined my day later this year if not discovered!
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Jim Harris, ATP, T38, EC/KC-135A/E/R, 2008 RV7A, 2nd owner, N523RM (2015)
Superior XPIO-360, Hartzel CS prop, Dual GRT Horizon EX with ARINC, EIS, Garmin 340, 335 w/WAAS gps, Dual 430s (non-WAAS), TruTrak 385 A/P with auto-level & auto-trim, Tosten 6 button Military Grips, FlightBox wired to EX, Dynon D10A w/battery backup, 406 MHz ELT. Custom Interior, New TS Flightline hoses, Great POH!
Retired - Living the dream - going broke!
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  #2  
Old 04-25-2020, 04:21 PM
Darren Kerns Darren Kerns is offline
 
Join Date: Feb 2005
Location: Indiana
Posts: 189
Default

Jim
I have the same exact engine on my RV7. I have found mine tight at all times. I have never found them to be loose.

Stay safe & good luck.

Darren Kerns
RV7 N599DT
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  #3  
Old 04-25-2020, 04:39 PM
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bjdecker bjdecker is offline
 
Join Date: Jun 2005
Location: Georgetown, TX
Posts: 950
Default

Nylon end nuts?

It's not a good idea to use AN364, AN365 nuts in hi temp environments (i.e. firewall forward). The "nylon" will degrade quickly and fail, allowing the nut to loosen, turn, fall off...
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RV-7 (Flying)
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  #4  
Old 04-25-2020, 07:25 PM
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Tankerpilot75 Tankerpilot75 is offline
 
Join Date: Jan 2015
Location: Oklahoma City, OK
Posts: 683
Default

Quote:
Originally Posted by bjdecker View Post
Nylon end nuts?

It's not a good idea to use AN364, AN365 nuts in hi temp environments (i.e. firewall forward). The "nylon" will degrade quickly and fail, allowing the nut to loosen, turn, fall off...
The A&P and I discussed this and felt like where these were located shouldn?t be a problem for the nuts, besides these are ?locking nuts? just helping to secure the primary nuts. Certainly better than no locking nuts at all given the recent discovery.
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Jim Harris, ATP, T38, EC/KC-135A/E/R, 2008 RV7A, 2nd owner, N523RM (2015)
Superior XPIO-360, Hartzel CS prop, Dual GRT Horizon EX with ARINC, EIS, Garmin 340, 335 w/WAAS gps, Dual 430s (non-WAAS), TruTrak 385 A/P with auto-level & auto-trim, Tosten 6 button Military Grips, FlightBox wired to EX, Dynon D10A w/battery backup, 406 MHz ELT. Custom Interior, New TS Flightline hoses, Great POH!
Retired - Living the dream - going broke!
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  #5  
Old 04-25-2020, 07:30 PM
RVDan RVDan is offline
 
Join Date: Jun 2012
Location: Frederick, MD
Posts: 942
Default

Quote:
Originally Posted by Tankerpilot75 View Post
Finishing up my annual condition inspection and the A&P and I were checking connections and nuts on FWF. Everything was tight and secure except when we got to the fuel injector throttle body. Only one of the four nuts securing it to the engine was tight. Two were so loose you could spin them with your fingers and one was totally gone. The engine still ran smoothly.

Replaced all star lock washers, replaced the missing nut and tightened all to torque. We then added four nylon end nuts on top of the existing nuts and secured them - there was just enough room on the studs.

My A&P said this was the first time he?s ever seen nuts loosened like this - especially if no one?s worked on the item. He distinctly remembers checking the throttle body last year and every thing appeared secure then.

Our question: My engine is the Superior XP IO-360 B1AA2, has anyone else found they?ve had to tighten these nuts due to them becoming loose? This could have really ruined my day later this year if not discovered!
Nuts were not properly torqued, or something in the stack up ( servo/ brackets/ gaskets) was not right.
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Frederick, MD
PA28-140
Hph 304CZ
RV6 built and sold
N199EC RV6A flying
Retired Aerospace Engineer and A&P/IA
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  #6  
Old 04-26-2020, 05:32 PM
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pazmanyflyer pazmanyflyer is offline
 
Join Date: Jul 2007
Location: Litchfield Park, AZ
Posts: 1,113
Default

A quote from Vic S. on this exact topic.

"While doing a prebuy on Friday on an RV-8 I noticed a nut missing from the aft fuel servo mounting stud. This is not the first one of these I have discovered missing on an airplane. I know standard practice has been to use a nut, a lock washer, and washer, but for many years now I have been using AN363 all metal stop nuts with a washer in these locations and I have never seen one come loose. You might consider it on your airplane."

Here's the thread: http://www.vansairforce.com/communit...ttle+body+nuts
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EAA Chapter 538 www.chapters.eaa.org/eaa538
Wittman Tailwind W8 N53CH (built & sold)
Pazmany PL-1 N2029 (bought & sold)
RV7 - N537TC (reserved & building)
Emp, Wings & Fuse done - working on FWF

"The air is an extremely dangerous, jealous and exacting mistress. Once under the spell most lovers are faithful to the end, which is not always old age." - Winston Churchill
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  #7  
Old 04-26-2020, 05:42 PM
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Greg Arehart Greg Arehart is offline
 
Join Date: Jul 2007
Location: Delta, CO/Atlin, BC
Posts: 2,435
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I agree with Vic/Carlos, if you want to be sure, use metal stop nuts.
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RV-9B (Big tires) Tipup @AJZ or CYSQ
N 7965A
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  #8  
Old 04-26-2020, 06:57 PM
VPYVO VPYVO is offline
 
Join Date: Sep 2011
Location: Melbourne Australia
Posts: 53
Default Yes indeed

Whilst I was completing my build another builder at our airfield had this same problem after 25hrs. Only one tight nut! The servo was about to fall off.
😳😳😳😳
I have added different types of metal locknuts. On top of the supplied ones.
one type is thin nut due lack of available threads.
Dont ask for part numbers as the docs are not handy.
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Melbourne Australia
RV7 VH-RRA flying Sept 2017
Sept 2019 180 hours
=VAF=. 2019 Donor
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  #9  
Old 04-26-2020, 08:25 PM
cajunwings cajunwings is offline
 
Join Date: Jun 2007
Location: new iberia la
Posts: 867
Default Loose hardware.

Metal locknuts are not a bad idea. The probability of the correct hardware and gaskets coming loose after being properly torqued is incredibly small. I?ve seen a couple cases where the wrong gasket (thicker & softer) was installed and even though properly torqued, over a week or two would compress and unload the lock washers and allow whatever component to become loose. Extremely important that the mags have the right gaskets. My experience is that fuel servos are not unusually prone to coming loose. Always a great idea at every condition inspection or 100 hrs of operation to check the torque on every fastener you can reach.

Don Broussard A&P/IA/ATP
RV9 Rebuild in Progress
57 Pacer
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  #10  
Old 04-26-2020, 10:01 PM
Jimzim Jimzim is offline
 
Join Date: Mar 2009
Location: Arvada, CO
Posts: 147
Default

Same setup on my RV7. No issues after 300 hours. I recommend torque seal here, to make verification easy.
Good luck and keep looking closely at everything...Jim
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2015 RV7,
Lyc Thunderbolt 0-360 A1A
Bendix FI
Hartzell BA CS
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