[thegasguy]

Can anyone tell me where the alternate static air source is on a PA28-140 cherokee cruiser?
It isnt where its shown to be in the poh ( left bottom side of instrument panel).
I imagine it must be in the cockpit area somewhere in reach of he pilot, but I cant find it!

[Keef]

Do you mean the knob you pull - if I remember right, on early PA28s it's under the bottom edge of the instrument panel, below the yoke - if fitted. I'm sure the instructors around will know.

If you mean "where does it get the alternate static air from" then the answer is "from behind the instrument panel." It's open to the cockpit, which is why it has some of the errors mentioned in the POH.

[thegasguy]

Keef, thanks for confirming where the knob to pull for alternate air should be. It isn't there!
The aircraft has just had an annual and has been maintained at the same place for ages so I guess it must be in there somewhere or else someone would have picked up on it.
I am going to ask the guys that maintain it this afternoon, if anyone is around on a Sunday.

Another rookie question: the ADF had an orange light come on and went a bit cranky the other day. I never encountered ADF in my training so I don't know what it means. Also "test" button? what does it actually test and what do I look out for?

I know I can Google it, but a proper pilots explanation is preferable if you have the time.

[Keef]

ADFs go cranky all the time. It's what they're for.
The orange light usually means it's switched on. Depending which model you have, it may mean it's hearing a signal.

The "test" button should make the ADF needle move smartly to a particular position. Usually 270, but I've seen them go all sorts of places.

[Keef]

Thinking about this, I recall one Cherokee I flew where the alt static was like a nail that swung horizontally through 90 degrees. When it was on normal static it was alongside the bottom of the panel and almost invisible.

[cotterpot]

Our PA28-140 didn't have a knob for alternate air, it was a break the glass job.
But then it was/is old - 1967

[Keef]

Break the VSI glass, as I recall. Never done that, but was looking forward to it in a certain aeroplane I flew many decades ago...

[thegasguy]

Wow! Flying along, the airspeed goes erratic, and so you take off your shoe and smash the VSI ! I can't see me doing that even if Its the proper procedure.
Can you imagine the reaction from any passenger?
A really sound QFI I flew with for a checkout in my new PA 28 last week said " learn the throttle settings for all phases of flight" I can see why now, ASI failure need not be a killer.
A passenger that thinks you have gone crazy could be!

[Keef]

Learning to fly with almost all the gauges covered up is excellent training - but don't try it until you've pretty much got the hang of flying the beast. You need to be able to detect and interpret controls getting mushy or super-stiff, the noise of the airflow round the aeroplane, the noise of the engine, and so on.

I doubt the loss of static would be a big deal for anyone trained by the right instructors. In good VMC, you really can fly without those instruments. On a windy, claggy day with no visibility it might be a tad character-building, though (not something to make a habit of!).

[johnm]

I doubt the loss of static would be a big deal for anyone trained by the right instructors. In good VMC, you really can fly without those instruments. On a windy, claggy day with no visibility it might be a tad character-building, though (not something to make a habit of!).

I've twice lost all pitot static instruments in solid IMC due failed pitot heater on PA28. It's not dramatic in the cruise as AI and DI and rev counter still work. Descent to loose the ice needed a little care and knowledge of power settings was very important!

[aerobuffet]

I own a 77 Archer. My ALT stuck at 1700 ft last week with no impact on the ASI or VSI. The CFI with whom I was flying asked if I had an alternate static source, to which I replied "no." However, in checking the POH, it was offered as an option so I'll be checking the underside of the dash tomorrow to determine if there is a valve there. Note, however, that the alternate requires closing all windows and vents and turning on the heater and defroster in order avoid having cabin pressure invalidate the alternate static source.

[ChrisRowland]

It seems strange to have the alternate static switch hidden out of sight under the panel, can't a pneumatic switch be put on the panel? It could even be labelled!

Not sure smashing the VSI glass will give a good static because the case is connected to aircraft static through a small leak. The value you get will depend on the rate of climb or descent.