That looks neat. The brushless motor is a big win for efficiency and avoiding the safety and servicing problems of brushed motors.
Any idea on the cost?
If we could put together an STC to use a system like that, and put it in the nose (to help with avionics upgrade tail heaviness), that would be awesome. I really have no idea what the BTU/hr of the current system is, but it sure wouldn't hurt to be more.
Joined: 11/06/20 Posts: 1614 Post Likes: +1686 Location: Tulsa, OK - KRVS
Aircraft: C501SP
Username Protected wrote:
It will also freak out passengers if the air is so cold i tis below dew point and the fog will look like smoke.
I had that once in my MU2 with the ACM.
We get that from the ACM on nearly all flights in the summer down here in the South. The CJP brain trust suggested turning on the freon system to try and dry the air and/or turning up the temp on the ACM.
The first time it happened I ended up turning the bleed air system off so I could see the runway.
Last edited on 12 May 2025, 12:37, edited 1 time in total.
Joined: 11/19/15 Posts: 1539 Post Likes: +1454 Company: Centurion LV and Eleusis Location: Draper UT KPVU-KVNY
Aircraft: N45AF 501sp Eagle II
Username Protected wrote:
It will also freak out passengers if the air is so cold i tis below dew point and the fog will look like smoke.
I had that once in my MU2 with the ACM.
We get that from the ACM on nearly all flights in the summer down here in the South. The CJP brain trust suggested turning on the freon system to try and dry the air and/or turning up the temp on the ACM.
The first time it happened I ended up turning the bleed air system off so I could see the runway.
I have had the same thing happen. The first time I wasn't expecting it, it was so bad I had to stop on the runway and let it clear a bit before I could taxi.
Now I make sure to turn on defrost at the top of decent and AC on as soon as I get under 18000. It helps for sure.
It will also freak out passengers if the air is so cold i tis below dew point and the fog will look like smoke.
I had that once in my MU2 with the ACM.
We get that from the ACM on nearly all flights in the summer down here in the South. The CJP brain trust suggested turning on the freon system to try and dry the air and/or turning up the temp on the ACM.
The first time it happened I ended up turning the bleed air system off so I could see the runway.
I had an ACM failure last summer coming out of HND back to Fort Worth. I couldnt control the temperature so it got extremely cold in the cabin. As I entered the pattern, the cabin filled with fog so bad I couldnt see. I didn't have the presence of mind to shut off the bleed air like you did! On top of that, when I landed, a squat switch failed, so I had no brakes and had to use the nitrogen bottle to stop the plane since it didnt have TR's. Not the best trip...
_________________ I'm just here for the free snacks
Have you cleaned the coalescer bag, checked the poppet valve, and/or checked the drain line from the water separator? That might help the humidity control.
Joined: 11/06/20 Posts: 1614 Post Likes: +1686 Location: Tulsa, OK - KRVS
Aircraft: C501SP
Username Protected wrote:
Have you cleaned the coalescer bag, checked the poppet valve, and/or checked the drain line from the water separator? That might help the humidity control.
Is that the "silk sock?" We removed it and washed it during my 1-4 a year ago. I also run my ACM in Auto mode so it should be deicing and such by itself. I have what is likely a dodgy temp sensor somewhere as when the plane is cold soaked (like single digits overnight on the ramp in Angel Fire, NM) it will trend the cabin colder and colder despite what I do with the temp knob. If I switch to manual I can get heat so I think the valves are fine. I haven't been sufficiently motivated to pull the plane and let it sit out overnight in the winter and then crawl around with a multimeter....
I'm not familiar with the drain line - I would assume that my mechanic would have looked at it when he R and R'd the sock?
I'm pretty sure it's related to ambient humidity as it is only a problem during the summer when coming into hot and humid locations but I am open to other's knowledge and experience.
I had an ACM failure last summer coming out of HND back to Fort Worth. I couldnt control the temperature so it got extremely cold in the cabin. As I entered the pattern, the cabin filled with fog so bad I couldnt see. I didn't have the presence of mind to shut off the bleed air like you did! On top of that, when I landed, a squat switch failed, so I had no brakes and had to use the nitrogen bottle to stop the plane since it didnt have TR's. Not the best trip...
Holy crap! That was a lot of stuff to go wrong on a single flight. One thing I like about my bird is that it is bare bones (except for the avionics). No TRs and manual brakes. Damn fine job stopping with nitrogen without blowing the tires - I have heard that in the heat of the moment (end of runway coming up fast), most people grab a handful of emergency brakes and lock up the tires. I have personally blown the gear down in my plane during a Phase 1-4 but I have never operated the emergency brake handle. I hope that if I ever need it that I will be able to slow her down gently...
I have actually had to use the nitrogen bottle twice on this same plane. They finally figured out the issue after this last time last summer. Its actually not that touchy. Fortunately I had a long runway so there was no panic. Both times I was able to taxi all the way to ramp by shutting down one engine and being judicious with the use of the bottle.
_________________ I'm just here for the free snacks
Is that the "silk sock?" We removed it and washed it during my 1-4 a year ago. I also run my ACM in Auto mode so it should be deicing and such by itself. I have what is likely a dodgy temp sensor somewhere as when the plane is cold soaked (like single digits overnight on the ramp in Angel Fire, NM) it will trend the cabin colder and colder despite what I do with the temp knob. If I switch to manual I can get heat so I think the valves are fine. I haven't been sufficiently motivated to pull the plane and let it sit out overnight in the winter and then crawl around with a multimeter....
I'm not familiar with the drain line - I would assume that my mechanic would have looked at it when he R and R'd the sock?
I'm pretty sure it's related to ambient humidity as it is only a problem during the summer when coming into hot and humid locations but I am open to other's knowledge and experience.
Yes on the silk sock. It's inside of the water separator. There is a drain line that runs from the water separator to one of the heat exchangers (if my memory serves me right). Old school technology. If that line is obstructed or the heat exchanger is full of crud, the water separator could be less effective. Those are just things I would be looking at. Your mechanic may have already done them.
I also wonder if the turbine speed is playing a role in this. The book says the ACM can't really do anything unless the throttle is more than half way up its travel range. (No specific turbine speed given.) Maybe pulling the power back on descent reduces air flow through the ACM which reduces the water separator's effectiveness. Just another theory.
I personally have not seen the fog on my airplane yet.
Joined: 11/15/17 Posts: 1065 Post Likes: +548 Company: Cessna (retired)
Username Protected wrote:
How old is your compressor?
My system was converted to R134a in 2012 which was a new compressor and condenser assembly, so relatively young. It is an automotive part.
This was unexpected since the maintenance tracking said it still had the R12 system in it when I bought the plane. So I lucked out and had the R134a conversion I didn't expect.
Quote:
When was the last time it was serviced?
Shortly after I bought the plane, I found the system setup all wrong. Wrong pressures, wrong balance, very poor performance, etc. It got carefully tuned and adjusted and now works decently. Also, all the evaporators fins were clogged with carpet dust. After 4 hours of carefully cleaning them, much better.
The freon system being way out of whack was one of many things wrong with my plane when I bought it. Almost all those things took very little money to fix, but took careful diagnosis to find the root cause. I don't think the Textron service center knew how to detect these problems or how to fix them without gratuitous part replacements.
Joined: 11/06/20 Posts: 1614 Post Likes: +1686 Location: Tulsa, OK - KRVS
Aircraft: C501SP
Username Protected wrote:
I personally have not seen the fog on my airplane yet.
Well, you do live in Arizona Come on over here to the South and you too can experience The Air you can Wear. A regular hop for us in the Summer is Oklahoma to the Alabama coast - we go from really humid to stupidly humid in the same trip.... I never have an issue in the winter.
We have some summer trips planned to that part of the country. One of my friends is a timid passenger. If I get the fog, he’s going to lose his mind. I can’t wait
You cannot post new topics in this forum You cannot reply to topics in this forum You cannot edit your posts in this forum You cannot delete your posts in this forum You cannot post attachments in this forum
BeechTalk, LLC is the quintessential Beechcraft Owners & Pilots Group providing a
forum for the discussion of technical, practical, and entertaining issues relating to all Beech aircraft. These include
the Bonanza (both V-tail and straight-tail models), Baron, Debonair, Duke, Twin Bonanza, King Air, Sierra, Skipper, Sport, Sundowner,
Musketeer, Travel Air, Starship, Queen Air, BeechJet, and Premier lines of airplanes, turboprops, and turbojets.
BeechTalk, LLC is not affiliated or endorsed by the Beechcraft Corporation, its subsidiaries, or affiliates.
Beechcraft™, King Air™, and Travel Air™ are the registered trademarks of the Beechcraft Corporation.