PA32-301R Air conditioner "guard"

[Ryan2]

Hi all -

Have a PA32-301R Saratoga with factory a/c. The factory setup has a plastic guard that sticks out about 4-5" from the evaporator into the baggage area.

Given we use the plan for travel with 2 small kids, that intrusion into the baggage area makes packing difficult. Was wondering if anyone know if there are any "lower profile" guards available that would take up less room/be less likely to get damaged than the plastic factor one.

I'm looking for a picture to demonstrate what I'm talking about, I'll post if I can find one ..

Thanks!

 

[Ryan2]

I did find it in a parts catalog -

It's called "evaporator filter cover" - #28 on this diagram

 

[Rgbeard]

I've never yet seen one with item 28 and 30 remaining in place.

 

[Ryan2]

That's interesting! We have one! Plan is actually having the panel redone or I'd go take a picture of it in the wild!

Of course two of the legs have been broken....

I was always under the assumption it was necessary for proper airflow to the evaporator ... is that not the case?

 

[Rgbeard]

That's interesting! We have one! Plan is actually having the panel redone or I'd go take a picture of it in the wild!

Of course two of the legs have been broken....

I was always under the assumption it was necessary for proper airflow to the evaporator ... is that not the case?

As far as I can tell it's there to simply hold a filter element in place. But I don't feel I'm properly qualified to answer the question.

 

[Salty]

Does it protrude into the lower baggage area, or the "hat rack" above and behind it? I wouldn't put anything of any weight on the hat rack area anyway, although curiously, I'm not finding any limitations or even mention of the area in the manual.

 

[Bell206]

I was always under the assumption it was necessary for proper airflow to the evaporator ... is that not the case?

FYI: any blocking of the evaporator inlet will decrease the efficiency of the system. The evaporator is what cools the air being sent out the overhead ducts. Your condenser is the hinged unit on the belly of the aircraft.

 

[Ryan2]

Thanks @Rgbeard

@Salty -It protrudes into the baggage area, not the hat rack. The parts diagram above makes it look not-so-bad, but it sticks out a good few inches for sure.

@Bell206 - Yeah, I kinda figure that would be the case. I guess my question is would it be effective enough with just 1" of clearance instead of 3-4"? I thought blocking it entirely would probably be sub-optimal ....

Also thank you for the clarification - I used the wrong term in my original post. I corrected it.

 

[Bell206]

I guess my question is would it be effective enough with just 1" of clearance instead of 3-4"?

No. Efficiency is all about air flow. And keep in mind the entire system is usually designed to operate at those air flows which can cause other problems. You can also keep the A/C off and pack the baggage full as an option.

 

[Ryan2]

No. Efficiency is all about air flow. And keep in mind the entire system is usually designed to operate at those air flows which can cause other problems. You can also keep the A/C off and pack the baggage full as an option.

Makes sense. Perhaps worthwhile to remove it in the cooler months where the a/c is not being used.

It's great to have a/c when taxiing and sitting on the ground, or when forced to cruise at lower altitudes but when we're traveling I rarely want to tolerate the 5-6kt penalty that that large intake scoop give us. And usually it's cool enough at altitude to just let the cabin vents take care of the cooling.

Thanks for the information.

 

[dfw11411]

This is from my Cherokee 6XT PA-32-301XTC which is supposed to be very similar to a Saratoga. If yours is similar to this I'd remove it and find a local Maker Lab or find someone who can scan, modify and 3D print a replacement with a lower profile. I'd suggest adding vent openings on the face to increase airflow. Or you could remove it and cover the filter with hardware cloth or grate for a zero profile.

 

[Ryan2]

@dfw11411 that's it exactly. Great picture, thanks for that.

3d printing is an interesting idea. Where would one go to find that? You mentioned a maker lab, I've never heard of that ....

Replacements are like $300 anyway - can't imagine it would cost a whole lot more to just make one myself lol

EDIT: then I looked up the cost to 3d scan and then print something. AND ... I think I'm wrong lol!

 

[Brad W]

as a life long jury-rig DIY'er I can imagine several decent solutions to that problem....
but I wonder how much modification is allowable on things like this without some sort of STC or other "paperwork"?
What if this was an experimental that you yourself had built, how would that be different in needing or getting approvals for mods like this?

A couple years ago I used two of the smaller size of this
https://www.westmarine.com/buy/west-marine--louvered-ventilator-black-4-7-8-x-10-1-8--P000282320
cut and epoxied together to make a rectangular version with the louvers going in the opposite direction from the off-the-shelf rectangular model. You've gotta look real close to determine it's a homemade jury rig....

Anyway, that one is not likely to be the size you need, but something like this is my first thought... with the identified problem that it's easier to block off the airflow totally with a soft sided duffle or an ill placed sweater if it was mounted flush to the filter.... mounting with some sort of stand-off frame to give some breathing space all around perhaps...
could do bad things to block that air return....which is probably why they have it designed the way they do...little less likely to choke it off all around the way it is

 

[Ryan2]

@Brad W Appreciate your input. Yeah, I believe @Bell206 as above. I'm sure there's a reason for it. It's just a lousy design and an ergonomic annoyance. I do wonder how much efficiency I would lose say if it were half of the depth. It also "stands off" with weak plastic legs - 2 of them are already broken, I've no doubt I'll eventually break it off (we travel with 2 kids and lots of crap....).

If it was left "open" (i.e. don't block it) I think it would be just fine and I could remove it entirely. however, I don't trust myself enough to do that. As I said, I generally only use the AC for taxi and climb out, because the outside airscoop is HUGE on these planes and results in a pretty significant speed penalty.

It is nice to have on those hot summer days though I will say that ....

have to do some more thinking, but appreciate your input.

 

[dfw11411]

Does this resolve the certified parts only problem?

 

[Bell206]

I wonder how much modification is allowable on things like this without some sort of STC or other "paperwork"?

Pulling the guard would be a simple alteration but would need an AP sign off. Its actually on the cusp of a preventative mx item except a pilot can't perform an alteration, legally. But looking at the pic its more a "spacer" than a guard to keep things away from the inlet. Even if you take it off you still couldn't put a bag there blocking the inlet provided you didnt want to affect the AC output. There are a number of aircraft evaporator inlets that are just flat screen as the one pictured under the "guard." I'd just pack light and stuff the bags in without collapsing the "guard."

 

[Salty]

‘Purt near anything you do to that will degrade the operation of the AC, it’s there for a reason. You can’t cool air that can’t flow through the AC system.

if you’re not using the ac it wouldn’t matter, but otherwise I’d want it as is.