Air Conditioning and Cabin Fans
I have a 1976 Piper Arrow II
I have 99.9% completed A panel Upgrade to make it a 2025 IFR Beast. Garmin Navigators, Auto Pilot, 2 G5s and engine monitor, ADSB in out Audio panel Etc
They told me upon inspection that the Air conditioning Fan and Cabin fans aren't working. I already knew this a told them it was because the AC was removed.
I asked if it was possible to put the Cabin fans back? I was told anything is possible but the fan may create electrical interference with the systems I just put in.
I'm reaching out to see if anyone has replaced a cabin fan for the the plane with these systems? was there and trouble with it?
Dean
Comments
Dean,
I hope you post some pictures of the new panel. Sounds awesome!
Was the panel upgrade performed by an avionics shop, and then a different shop - maybe the one performing your maintenance and inspections - issued the warning about potential interference problems when adding a fan?
We're usually only concerned about motor EMI (interference) in the AM radio bands (1 MHz), down where ADF receivers operate. But your aircraft probably left the factory with both a blower motor and an ADF receiver, and they interoperated just fine. Your new electronics has receivers at 100 MHz (Nav/Comm), 1 GHz (ADSB) and 1.5 GHz (GPS Navigators) - all well outside the bands where a fan makes interference. Highly unlikely to be an issue. And in the unlikely event there is an issue, avionics shops carry a wide range of inline LC filters that will mitigate the problem.
Funny story: a few years ago, NHTSA revoked Tesla's production authorization for their Model 3. During development of the Model 3, Tesla observed that their fancy power electronics generates so much interference as to render the in-dash AM radio unusable on all stations. Rather than fix the power electronics, Tesla "solved," the problem by eliminating the AM radio, reasoning, "no one listens to AM anymore." NHTSA had a different view, based upon the fact that an AM radio is required to receive the Emergency Broadcast Service, and all production automobiles must be capable of receiving EBS to be street legal. Eventually Tesla relented, fixed the EMI problem and reenabled the AM radio, and was permitted to resume selling the car.
Bob
Interesting story Bob. Im in Canada and listen to AM still I like talk radio when I'm driving. Toronto its 1010.
It is an avionics shop doing all my work. I'll pass on the message.
Dean
The factory fans for both the overhead and air conditioning should not have any effect on any installed avionics in a Piper airplane. If they do then the avionics installation people have some grounds really screwed up.
48 yrs A/P IA DAL aircraft inspector. 172N
Looks like the key word we are dancing around is: "...may..."
Unless I am missing something, as long as approved parts go into the plane, they should not cause interference with each other as this is why they cost a lot more money than their generic corner store bought counterpart.
So I agree with the comment that if there is any interference, it will most likely come from poor connections, or possibly dirty power, and not the component itself.
But... At the moment we are playing a hypothetical game and can argue just about anything. The real test is (correctly) installing the approved part and seeing if there is anything further to address.
Thank you everyone.
I think my next question would be..... Has anyone ever removed the air conditioning and then decided to put the cabin fan back?
The cabin fan is totally separate from the air conditioning system. The cabin fan is supported from the overhead and provides your overhead air to the air vents. Carl
48 yrs A/P IA DAL aircraft inspector. 172N
Thanks Carl
Educational, I was of the belief it was all in one. Im going to open it up when I get it back and take a look to see which parts are there or not there
Dean