Control surface repair legal?

[[email protected]]

OK... I've got a question. I've seen a number of aircraft around that have
had little patches and repairs made on them. Sometimes on a wing or fuselage,
sometimes on an elevator, sometimes on an aileron. I've heard that it is illegal to
patch moveable control surfaces, but yet I've seen numerous aircraft around with
repairs like that.

Does anyone know if this is true/false and which regs (chapter and verse)
dictate it?

Just curious...
-Cory

--

************************************************** ***********************
* Cory Papenfuss, Ph.D., PPSEL-IA *
* Electrical Engineering *
* Virginia Polytechnic Institute and State University *
************************************************** ***********************

[[email protected]]

wrote:
> OK... I've got a question. I've seen a number of aircraft around that have
> had little patches and repairs made on them. Sometimes on a wing or fuselage,
> sometimes on an elevator, sometimes on an aileron. I've heard that it is illegal to
> patch moveable control surfaces, but yet I've seen numerous aircraft around with
> repairs like that.
>
> Does anyone know if this is true/false and which regs (chapter and verse)
> dictate it?
>
> Just curious...
> -Cory
>

Depends what the manufacturer has to say in the Service Manual or
Structural Repair manual. Cessna publishes repair procedures for their
light airplanes, including control surfaces, in the Structural Repair
chapter of their manuals.
A repair is one thing. Upsetting the mass balance of a control
surface with a repair is a serious offence, and one needs to be careful
about keeping things right.

Dan

[Frank Stutzman]

wrote:
> Depends what the manufacturer has to say in the Service Manual or
> Structural Repair manual. Cessna publishes repair procedures for their
> light airplanes, including control surfaces, in the Structural Repair
> chapter of their manuals.
> A repair is one thing. Upsetting the mass balance of a control
> surface with a repair is a serious offence, and one needs to be careful
> about keeping things right.

Perfectly correct.

In counterpoint to Dan's example, Beech does not allow *ANY* repairs on the magnesium
ruddervators on a early Bonanza. After seeing how tight the balance is on those things I
wholeheartedly agree. I would be very leary of an early Bonanza that even had bad paint on its
ruddervators.

--
Frank Stutzman
Bonanza N494B "Hula Girl"
Hood River, OR

[[email protected]]

Hrm... so again I guess the answer is, "it depends."

Frank Stutzman > wrote:
: wrote:
: > Depends what the manufacturer has to say in the Service Manual or
: > Structural Repair manual. Cessna publishes repair procedures for their
: > light airplanes, including control surfaces, in the Structural Repair
: > chapter of their manuals.
: > A repair is one thing. Upsetting the mass balance of a control
: > surface with a repair is a serious offence, and one needs to be careful
: > about keeping things right.

: Perfectly correct.

: In counterpoint to Dan's example, Beech does not allow *ANY* repairs on the magnesium
: ruddervators on a early Bonanza. After seeing how tight the balance is on those things I
: wholeheartedly agree. I would be very leary of an early Bonanza that even had bad paint on its
: ruddervators.

: --
: Frank Stutzman
: Bonanza N494B "Hula Girl"
: Hood River, OR


--

************************************************** ***********************
* Cory Papenfuss, Ph.D., PPSEL-IA *
* Electrical Engineering *
* Virginia Polytechnic Institute and State University *
************************************************** ***********************

[Robert M. Gary]

wrote:
> OK... I've got a question. I've seen a number of aircraft around that have
> had little patches and repairs made on them. Sometimes on a wing or fuselage,
> sometimes on an elevator, sometimes on an aileron. I've heard that it is illegal to
> patch moveable control surfaces, but yet I've seen numerous aircraft around with
> repairs like that.

Flight controls are balanced to prevent flutter (something that can
kill you pretty fast). Any changes to the control surface require the
surface to be removed and balance checked unless the manufactor has
another method of compliance.

-Robert

[[email protected]]

: Flight controls are balanced to prevent flutter (something that can
: kill you pretty fast). Any changes to the control surface require the
: surface to be removed and balance checked unless the manufactor has
: another method of compliance.

I am aware that they needed to stay balanced to prevent flutter... but I'd heard that just as an
overriding rule, moveable control surfaces are unrepairable.

I looked through my Cherokee service manual as an example. It doesn't specifically forbid control surface
repair, but it seems to imply that it's allowable... so long as it's within the balance limits. In fact, it says,

"Where possible the control surfaces were set with the balance weight on the heavy side of the limits, to
permit limited repair or paint touch-up without adjusting the balance weight."

and
"All replacement control surfaces, or surfaces that have been repainted or repaired, should be rebalanced
according to the procedures given in Paragraphs...blah,blah"

Seems that at least in the case of a Cherokee it's OK... provided they stay within balance limits.

-Cory

--

************************************************** ***********************
* Cory Papenfuss, Ph.D., PPSEL-IA *
* Electrical Engineering *
* Virginia Polytechnic Institute and State University *
************************************************** ***********************

[RST Engineering]

And I heard (and read) that the streets in Califia are paved with gold.
What you heard is not true. As you read (and posted) your Cherokee manual
specifically says that they added mass balance to the heavy limit to allow
for paint AND REPAIRS. (Emphasis author.) I'm not sure whether that is
implicit or explicit acknowledgement that repairs can be made, but it
certainly is one or the other.

Jim



> wrote in message
...
>
> I am aware that they needed to stay balanced to prevent flutter... but I'd
> heard that just as an
> overriding rule, moveable control surfaces are unrepairable.

[Robert M. Gary]

wrote:
> I am aware that they needed to stay balanced to prevent flutter... but I'd heard that just as an
> overriding rule, moveable control surfaces are unrepairable.
>
> I looked through my Cherokee service manual as an example. It doesn't specifically forbid control surface
> repair, but it seems to imply that it's allowable... so long as it's within the balance limits. In fact, it says,
>
> "Where possible the control surfaces were set with the balance weight on the heavy side of the limits, to
> permit limited repair or paint touch-up without adjusting the balance weight."
>
> and
> "All replacement control surfaces, or surfaces that have been repainted or repaired, should be rebalanced
> according to the procedures given in Paragraphs...blah,blah"
>
> Seems that at least in the case of a Cherokee it's OK... provided they stay within balance limits.

BTW: Paint shops are specificlly certificated by the FAA because of the
possibility of getting controls out of balance. I know of no paint shop
that paints control surfaces without removing the surface first and
balancing it afterwards in any aircraft.

I had a truck back into my Mooney's aileron in Mexico. When I got it
back to the U.S. the Mooney Service Center said that, although they
could reskin and repair the damage they didn't think I'd ever be happy
with the results. They said they've never seen a repaired surface fly
straight. As a result we bought the $2300 new aileron from Mooney. Now
I'm sure some people in the back woods bend their control surfaces back
and are happy with them but other pilots are pretty picky and the
Service Center needs to accomidate that.
Some people drive Fords and are happy bending metal and others drive
Caddys and expect a certain "ride.

-Robert

[pbc76049]

There is no reg specifically prohibiting control surface repairs.
You won't find chapter and verse because a reg on this doesn't exist.
Each aircraft has its own repair methods called out in the aircraft manuals
OR AC43
Next question.....

> wrote in message
...
> OK... I've got a question. I've seen a number of aircraft around that
> have
> had little patches and repairs made on them. Sometimes on a wing or
> fuselage,
> sometimes on an elevator, sometimes on an aileron. I've heard that it is
> illegal to
> patch moveable control surfaces, but yet I've seen numerous aircraft
> around with
> repairs like that.
>
> Does anyone know if this is true/false and which regs (chapter and verse)
> dictate it?
>
> Just curious...
> -Cory
>
> --
>
> ************************************************** ***********************
> * Cory Papenfuss, Ph.D., PPSEL-IA *
> * Electrical Engineering *
> * Virginia Polytechnic Institute and State University *
> ************************************************** ***********************
>

[[email protected]]

>From the responces, it appears that some repair manuals allow repairs
to control surfaces. However, it needs to be mentioned that
structurally a repair is OK as long as the balance is maintained.
However, repairs often include patches that can cause a disruption of
the airflow, especially if done like some repairs I have seen. If the
surface contour is maintained, and the balance done right, a repair
should be OK. I don't see how an aileron crushed by a truck could ever
be made straight again for less effort than a new one would cost.
Bonanza ruddervators and Mooney ailerons are both notorius for needing
to be exact.

Bud

wrote:
> OK... I've got a question. I've seen a number of aircraft around that have
> had little patches and repairs made on them. Sometimes on a wing or fuselage,
> sometimes on an elevator, sometimes on an aileron. I've heard that it is illegal to
> patch moveable control surfaces, but yet I've seen numerous aircraft around with
> repairs like that.
>
> Does anyone know if this is true/false and which regs (chapter and verse)
> dictate it?
>
> Just curious...
> -Cory
>
> --
>
> ************************************************** ***********************
> * Cory Papenfuss, Ph.D., PPSEL-IA *
> * Electrical Engineering *
> * Virginia Polytechnic Institute and State University *
> ************************************************** ***********************

[[email protected]]

>From the responces, it appears that some repair manuals allow repairs
to control surfaces. However, it needs to be mentioned that
structurally a repair is OK as long as the balance is maintained.
However, repairs often include patches that can cause a disruption of
the airflow, especially if done like some repairs I have seen. If the
surface contour is maintained, and the balance done right, a repair
should be OK. I don't see how an aileron crushed by a truck could ever
be made straight again for less effort than a new one would cost.
Bonanza ruddervators and Mooney ailerons are both notorius for needing
to be exact.

Bud

wrote:
> OK... I've got a question. I've seen a number of aircraft around that have
> had little patches and repairs made on them. Sometimes on a wing or fuselage,
> sometimes on an elevator, sometimes on an aileron. I've heard that it is illegal to
> patch moveable control surfaces, but yet I've seen numerous aircraft around with
> repairs like that.
>
> Does anyone know if this is true/false and which regs (chapter and verse)
> dictate it?
>
> Just curious...
> -Cory
>
> --
>
> ************************************************** ***********************
> * Cory Papenfuss, Ph.D., PPSEL-IA *
> * Electrical Engineering *
> * Virginia Polytechnic Institute and State University *
> ************************************************** ***********************