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Tunnel Access Panel Question
- Thread starter BJohnson
- Start date
As someone who has done a few condition inspections on a 10 I find one tunnel side access panel to be extremely helpful. I don't think two are necessary but I haven't had a plane with two of them.
It depends on a few things though. If your fuel filter will be in the tunnel and/or if you have a lower center console that makes removing the top of the tunnel difficult then the access panel is even more useful.
For the 10 I'm building I put one access panel on the right side of the tunnel. I also did wing root fuel filters. My expectation is that for condition inspection I can remove only the side panel to inspect the fuel pump.
I assume if I need to remove the fuel pump I'll also need to remove the top of the tunnel. If so, I don't have a lower center in the way. I also cut the big long tunnel top into three pieces and added additional nutplates and doublers. This allows me to remove any of the three sections separately.
It depends on a few things though. If your fuel filter will be in the tunnel and/or if you have a lower center console that makes removing the top of the tunnel difficult then the access panel is even more useful.
For the 10 I'm building I put one access panel on the right side of the tunnel. I also did wing root fuel filters. My expectation is that for condition inspection I can remove only the side panel to inspect the fuel pump.
I assume if I need to remove the fuel pump I'll also need to remove the top of the tunnel. If so, I don't have a lower center in the way. I also cut the big long tunnel top into three pieces and added additional nutplates and doublers. This allows me to remove any of the three sections separately.
Put the least amount of items in the tunnel as you can. You will be happy later…
Auburntsts
Well Known Member
I have one access panel mainly to access the fuel filter but also it gives me access to examine/inspect the components in the forward tunnel (fuel pump, fuel and brake lines, the fuel selector valve, fittings, etc) without having to remove my stock forward tunnel cover which is a bit of a PITA IMO. I put my borescope to good use to make my examinations/inspections easier. With a stock tunnel, I don't see any advantage to installing 2 access panels. My thoughts after 12 CIs.
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I have one, starboard side. It helps somewhat with fuel filter fittings access. Frankly however, even with it, removing and then reinstalling the fuel filter post inspection is still a (necessary) PITA.
If I were building, I’d probably go the wing root filters route. Just my $0.02.
If I were building, I’d probably go the wing root filters route. Just my $0.02.
Mike S
Senior Curmudgeon
Yes, and do both sides.
For this second RV-10 build I looked at the PITA fuel filter inspection process. I looked hard at wing root filters but ended up discarding the idea. Every example I found of wing root filters I noted several added 90 degree fuel fittings. I made many decisions to maintain the capability of someday running mogas as a hedge against future 100LL cost and availability. 90 degree fittings are on the no list to mitigate vapor lock. Before everyone jumps in about SDS and high fuel pressure, I ruled out SDS for other reasons.
I also decided against a filter access panel. Looking at examples (and gaining proficiency at using crow’s feet and such) the access panel became less valuable for me.
But, I do offer and easy mod addressing the “cram it in there” rear seat SCAT hose issue. On both builds I replaced the 2” SCAT hose with a 1.5” hose. The new build does this via 3D printed reducers. I can report there is still a bunch of heat available to the rear passengers.
Carl
I also decided against a filter access panel. Looking at examples (and gaining proficiency at using crow’s feet and such) the access panel became less valuable for me.
But, I do offer and easy mod addressing the “cram it in there” rear seat SCAT hose issue. On both builds I replaced the 2” SCAT hose with a 1.5” hose. The new build does this via 3D printed reducers. I can report there is still a bunch of heat available to the rear passengers.
Carl
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I wouldn't dispute anyone's opinion and experience with the tunnel and what may or may not work better.
Taking the tunnel cover off and doing any kind of work down inside of it is not easy under any circumstances.
I do not have access holes on either side of the tunnel and both the red cube as well as the fuel pump are installed inside the tunnel.
Those 2 items need little or no maintenance, at least in my airplane. My filters (2) are installed under the seats, one for the left and one for the right.
Access is very convenient, only downside is you need 2 of them. (serviceable airflow performance filters)
When doing annual CI it is fair to assume that your seats are out and you probably should have at least visual access to all of the tunnel not just what you might see through an access hole or with a camera. When the seats are removed, it is a fairly easy task to remove the tunnel cover provided you outfit yourself with the right tools before you stretch out under the panel.
The key is not putting anything down into the tunnel that needs service, like the fuel filter. I most certainly would not extend the instrument panel downward to obstruct access to the tunnel cover.
An access hole might offer convenience under certain circumstances for tool reach and such but thinking that you could actually fix something through an access hole is a bit of a stretch not to mention containing a fuel spill while servicing a filter.
The tunnel sidewalls are around .040 gauge material if I recall and must be of some structural importance, me thinks.
Taking the tunnel cover off and doing any kind of work down inside of it is not easy under any circumstances.
I do not have access holes on either side of the tunnel and both the red cube as well as the fuel pump are installed inside the tunnel.
Those 2 items need little or no maintenance, at least in my airplane. My filters (2) are installed under the seats, one for the left and one for the right.
Access is very convenient, only downside is you need 2 of them. (serviceable airflow performance filters)
When doing annual CI it is fair to assume that your seats are out and you probably should have at least visual access to all of the tunnel not just what you might see through an access hole or with a camera. When the seats are removed, it is a fairly easy task to remove the tunnel cover provided you outfit yourself with the right tools before you stretch out under the panel.
The key is not putting anything down into the tunnel that needs service, like the fuel filter. I most certainly would not extend the instrument panel downward to obstruct access to the tunnel cover.
An access hole might offer convenience under certain circumstances for tool reach and such but thinking that you could actually fix something through an access hole is a bit of a stretch not to mention containing a fuel spill while servicing a filter.
The tunnel sidewalls are around .040 gauge material if I recall and must be of some structural importance, me thinks.
I’ve got two of the original Aerolab filters thankfully on my 10 so don’t need to access the tunnel for filter changes.
However.. the single access panel is invaluable for getting to all the other b nuts on the fuel selector and forward.
However.. the single access panel is invaluable for getting to all the other b nuts on the fuel selector and forward.
I cut up the tunnel cover and added splice plates and nutplates so I can easily remove the 18" (or maybe 24") directly in front of the seats. No additional access is necessary for me to inspect the pump and filter and to remove, clean, and reinstall the filter.
As Bob has stated less is more in the tunnel. I have the pumps in the tunnel with one access door. Pre pump filter originally, I had in the wing root but wanted to use a decent pleated cleanable SS filter and had to use more 90's than desired. Went with the install under the seats (Andair 62-micron SS cleanable pleated filter) as I can get to them in 10 mins and easy. Post filter (10-micron Fuelab FWF). Also added an industrial shut-off valve since I had the room. Very low pressure drop.
Good luck !
Good luck !
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