Frozen Flaps

I am still familiarizing with a newly acquired 150.
The other day I flew on a chilly evening just above freezing.
I applied flaps in the pattern, and when I landed, the flaps didn't want
to retract
I had earlier exercised the flaps on preflight without problem
and before the plane was put away, the flaps went up OK.

I guessed that the actuator froze up, so it probably needs lube to keep
the water away.... The flap motor fuse checked OK of course...

Any thoughts?

Brian W

brian whatcott wrote:
I am still familiarizing with a newly acquired 150.
The other day I flew on a chilly evening just above freezing.
I applied flaps in the pattern, and when I landed, the flaps didn't want
to retract
I had earlier exercised the flaps on preflight without problem
and before the plane was put away, the flaps went up OK.

I guessed that the actuator froze up, so it probably needs lube to keep
the water away.... The flap motor fuse checked OK of course...

Any thoughts?

Brian W

Brian,

The most common cause of "frozen flaps" in Cessnas like yours are the
limit switches on the flap actuator, rather than the actuator itself. A
judicious application of a heat gun, through the appropriate inspection
panel, will free them up for a while. They are relatively inexpensive
to replace, however, and that's what is needed for a more permanent fix.

Happy Flying!
Scott Skylane

On Dec 13, 3:35 pm, Scott Braddock wrote:

The most common cause of "frozen flaps" in Cessnas like yours are the
limit switches on the flap actuator, rather than the actuator itself. A
judicious application of a heat gun, through the appropriate inspection
panel, will free them up for a while. They are relatively inexpensive
to replace, however, and that's what is needed for a more permanent fix.

Those little microswitches get oil in them from the jackscrew
threads, and the oil draws dust and crud and gunks up the switch
contacts with sludge. In the cold the sludge will congeal and make the
switch's mechanism stick, too. Replacing them is the best thing, and
you want to do it soon. If you had to abort a landing and go around,
the flaps on a 150/152 will hurt the climbout dangerously; there's
just too much drag.

Dan

On Mon, 14 Dec 2009 03:02:00 -0500, Jeffrey Bloss wrote:

On Sun, 13 Dec 2009 22:45:18 GMT, wrote:

On Dec 13, 3:35 pm, Scott Braddock wrote:

The most common cause of "frozen flaps" in Cessnas like yours are
the limit switches on the flap actuator, rather than the actuator
itself. A judicious application of a heat gun, through the
appropriate inspection panel, will free them up for a while.
They are relatively inexpensive to replace, however, and that's
what is needed for a more permanent fix.

Those little microswitches get oil in them from the jackscrew
threads, and the oil draws dust and crud and gunks up the switch
contacts with sludge. In the cold the sludge will congeal and make
the switch's mechanism stick, too. Replacing them is the best
thing, and you want to do it soon. If you had to abort a landing
and go around, the flaps on a 150/152 will hurt the climbout
dangerously; there's just too much drag.

There's too much jackscrew grease or the lube's spreading too easily if
its getting to the switches. Get it right. Alaskan 261 was running a
failing jackscrew which looked like lube drift.

I thought the 261 failed because it wasn't lubricated, maybe not. What
that has to do with a 150/2, I have no clue.

brian whatcott wrote:
I am still familiarizing with a newly acquired 150.
The other day I flew on a chilly evening just above freezing.
I applied flaps in the pattern, and when I landed, the flaps didn't want
to retract
I had earlier exercised the flaps on preflight without problem
and before the plane was put away, the flaps went up OK.

I guessed that the actuator froze up, so it probably needs lube to keep
the water away.... The flap motor fuse checked OK of course...

Any thoughts?

Brian W

When I had the Skyhawk and cleaning of relube of the jack screw for the
flaps was mandatory at annual. Has this been done? Or the motor can be
wearing out. the track on the flap rollers needs lubrication also.

--

Regards, Ross
C-172F 180HP
Sold
KSWI

wrote:
On Dec 13, 3:35 pm, Scott Braddock wrote:

The most common cause of "frozen flaps" in Cessnas like yours are the
limit switches on the flap actuator, rather than the actuator itself. A
judicious application of a heat gun, through the appropriate inspection
panel, will free them up for a while. They are relatively inexpensive
to replace, however, and that's what is needed for a more permanent fix.

Those little microswitches get oil in them from the jackscrew
threads, and the oil draws dust and crud and gunks up the switch
contacts with sludge. In the cold the sludge will congeal and make the
switch's mechanism stick, too. Replacing them is the best thing, and
you want to do it soon. If you had to abort a landing and go around,
the flaps on a 150/152 will hurt the climbout dangerously; there's
just too much drag.

Dan


Thanks to Scott and Dan for the insightful hints on flap limit switches.


Brian W

On Dec 14, 1:02*am, Jeffrey Bloss wrote:

There's too much jackscrew grease or the lube's spreading too easily if
its getting to the switches. Get it right. Alaskan 261 was running a
failing jackscrew which looked like lube drift.
--

Huh. I wonder if you've ever had anything to do with these things?
Cessna calls for SAE 10 non-detergent oil on the jackscrew every 100
hours. The microswitches are mounted immediately below the jackscrew
and sooner or later the oil gets onto and into them. It's a poor
setup. The older airplanes get moly disulphide grease.

Alaska's problem was too little of the right lube. It was a stab
actuator jackscrew, not a flap jack, and once the screw's nut threads
failed the stab did its own thing. If a flap jackscrew fails it'll
either jam in some position or the flaps will retract. The airplane is
still flyable. Cessna has other flap problems, like the roller sleeves
slipping sideways on their bearings and cutting a disc out of the flap
support arm and causing flap jamming. There was an SB on that in '96
or so. The only bits on the flap itself that need a little oil are the
flap roller bearings, not the tracks. Oiling the tracks attracts dirt
and lets the rollers slip instead of roll and they'll get flat spots.

Dan

On Mon, 14 Dec 2009 11:42:52 -0800 (PST),
wrote:

On Dec 14, 1:02*am, Jeffrey Bloss wrote:

There's too much jackscrew grease or the lube's spreading too easily if
its getting to the switches. Get it right. Alaskan 261 was running a
failing jackscrew which looked like lube drift.
--

Huh. I wonder if you've ever had anything to do with these things?
Cessna calls for SAE 10 non-detergent oil on the jackscrew every 100
hours. The microswitches are mounted immediately below the jackscrew
and sooner or later the oil gets onto and into them. It's a poor
setup. The older airplanes get moly disulphide grease.

Alaska's problem was too little of the right lube. It was a stab
actuator jackscrew, not a flap jack, and once the screw's nut threads
failed the stab did its own thing. If a flap jackscrew fails it'll
either jam in some position or the flaps will retract. The airplane is
still flyable. Cessna has other flap problems, like the roller sleeves
slipping sideways on their bearings and cutting a disc out of the flap
support arm and causing flap jamming. There was an SB on that in '96
or so. The only bits on the flap itself that need a little oil are the
flap roller bearings, not the tracks. Oiling the tracks attracts dirt
and lets the rollers slip instead of roll and they'll get flat spots.

Dan

Jeffrey's struggling, let's all bow and say a prayer for him :0)

Ross wrote:

When I had the Skyhawk and cleaning of relube of the jack screw for the
flaps was mandatory at annual. Has this been done? Or the motor can be
wearing out. the track on the flap rollers needs lubrication also.

Good question. I don't see a record of the jackscrew lube on the last
annual - but I haven't looked for it either....

Thanks

Brian W

On Dec 14, 2:42*pm, wrote:
On Dec 14, 1:02*am, Jeffrey Bloss wrote:

There's too much jackscrew grease or the lube's spreading too easily if
its getting to the switches. Get it right. Alaskan 261 was running a
failing jackscrew which looked like lube drift.
--

* Huh. I wonder if you've ever had anything to do with these things?

Dan

Hi Dan. What you wanna do is never respond to that poster
again, or better yet, killfile that name. It reads our posts,
runs to google to "brush up", then hurrys back to insult you.
Killfile it or don't ever read it or answer.

---
Mark