NTSB Safety Alert CH 601

Here's a model report on treating home-builders like grownups.
Highlights:
Mass balancing controls - tight control wires not enough

Reduced stick force per G at higher G made worse by aft CofG

Don't push the stick hard by mistake - it may be your last.

http://www.ntsb.gov/recs/letters/2009/A09_30_37.pdf

Brian W

On Apr 19, 5:49*am, Brian Whatcott wrote:
Here's a model report on treating home-builders like grownups.
Highlights:
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For anyone unfamiliar with bureaucratic formats, skipping to the last
page of the 12 page report, will give you a complete list of the
highlights. But the real message is more subtle than it appears. The
real message offers a polite Heads-Up to ALL American airmen, telling
us that if we can't keep our house in order there are plenty of
bureaucrats more than eager to jump in and take care of that little
matter for us. (Need I mention that bureaucrats don't come cheap?)

I STRONGLY suggest you read the whole report and be prepared to act on
it accordingly, when appropriate.

-R.S.Hoover

"Bob Hoover" wrote

For anyone unfamiliar with bureaucratic formats, skipping to the last
page of the 12 page report, will give you a complete list of the
highlights. But the real message is more subtle than it appears. The
real message offers a polite Heads-Up to ALL American airmen, telling
us that if we can't keep our house in order there are plenty of
bureaucrats more than eager to jump in and take care of that little
matter for us. (Need I mention that bureaucrats don't come cheap?)

I STRONGLY suggest you read the whole report and be prepared to act on
it accordingly, when appropriate.

-R.S.Hoover

***********************************************8
Zactly. Even better, I can't imagine flying a plane that might come apart
in mid air (for no apparent reason) without fixing the problem causing it to
come apart. Perhaps people should consider that fact, too.

Does anyone know why there is no mass ballancing (as is common practice) on
the ailerons, in the first place?
--
Jim in NC

On Apr 19, 3:15*pm, "Morgans" wrote:

Does anyone know why there is no mass ballancing (as
is common practice) on the ailerons, in the first place?

Mass balancing of ailerons may be common, but it is far from
universal. The majority of the Aeroncas and T-carts and high-wing
Pipers that are such a large part of the GA fleet do not have aileron
mass balancing.

Since mass balancing will often triple the mass of the surface to
which it is applied, it can have a serious effect on performance and
useful load.

Furthermore, even many fast (200 mph or so) airplanes that do have
mass-balanced ailerons are not 100% mass balanced. This category
includes Vans RV-series airplanes.

Thanks, Bob K.

Brian Whatcott wrote:
Here's a model report on treating home-builders like grownups.

I sure hope you're being facetious, since it asks that even experimental
aircraft be grounded, even though it contradictorily also states some
aircraft built from that design have already made design changes that make
the cited concerns mute.

The report also references material from the Matronics Zenith e-mail list
and uses it as supporting circumstantial evidence (the core argument is an
entirely circumstantial one of course.) Considering the total lack of
authentication of such e-mail material, it's a bit irresponsible to build
an already questionable circumstantial case on unauthenticated claims.
Also, I've browsed that list and the hysteria and infighting concerning
this issue in that e-mail list almost puts Usenet to shame.

There may indeed be a problem with the 601 design, though the report is
something of a shot-gun affair re causal factors. I guess if they put in
enough issues they can hope to later say "we told you so" no matter the
cause(s) found for the cited accidents.

Bob Kuykendall wrote:
On Apr 19, 3:15 pm, "Morgans" wrote:

Does anyone know why there is no mass balancing (as
is common practice) on the ailerons, in the first place?

Mass balancing of ailerons may be common, but it is far from
universal. The majority of the Aeroncas and T-carts and high-wing
Pipers that are such a large part of the GA fleet do not have aileron
mass balancing.

Since mass balancing will often triple the mass of the surface to
which it is applied, it can have a serious effect on performance and
useful load.

Furthermore, even many fast (200 mph or so) airplanes that do have
mass-balanced ailerons are not 100% mass balanced. This category
includes Vans RV-series airplanes.

Thanks, Bob K.


Fair comments.... some aircraft use fractional balancing - in the 1/2 to
2/3 region as a weight-saving measure. A hinge line aft of the aileron
leading edge is another tactic.

Brian W

Brian Whatcott wrote:
Here's a model report on treating home-builders like grownups.
Highlights:
Mass balancing controls - tight control wires not enough

Reduced stick force per G at higher G made worse by aft CofG

Don't push the stick hard by mistake - it may be your last.

http://www.ntsb.gov/recs/letters/2009/A09_30_37.pdf

Brian W


I forgot to mention a tactic used for improving pitch stick force per G.
Where an elevator rod or wire is connected by a pulley wheel or lever
- a mass on a fore and aft lever arm from the pivot provides a turning
moment which increases with increasing g, so as to increase the reaction
to elevator control force with g. This was the tactic used on the
Spitfire, if I remember....
There's another mass that is not structural like surface balances.

Brian W

Brian Whatcott wrote:
Bob Kuykendall wrote:
On Apr 19, 3:15 pm, "Morgans" wrote:

Does anyone know why there is no mass balancing (as
is common practice) on the ailerons, in the first place?

Mass balancing of ailerons may be common, but it is far from
universal. The majority of the Aeroncas and T-carts and high-wing
Pipers that are such a large part of the GA fleet do not have aileron
mass balancing.

Since mass balancing will often triple the mass of the surface to
which it is applied, it can have a serious effect on performance and
useful load.

Furthermore, even many fast (200 mph or so) airplanes that do have
mass-balanced ailerons are not 100% mass balanced. This category
includes Vans RV-series airplanes.

Thanks, Bob K.


Fair comments.... some aircraft use fractional balancing - in the 1/2 to
2/3 region as a weight-saving measure. A hinge line aft of the aileron
leading edge is another tactic.

Brian W

Below 120 knots or so, the excitation frequency from airflow is probably too low
to get too excited about (if you were an aileron, anyway).

Above that, things get closer to the fundamental excitation frequency of the
structure.


Richard

On Apr 19, 6:39 pm, Brian Whatcott wrote:

I forgot to mention a tactic used for improving pitch stick force per G.
Where an elevator rod or wire is connected by a pulley wheel or lever
- a mass on a fore and aft lever arm from the pivot provides a turning
moment which increases with increasing g, so as to increase the reaction
to elevator control force with g. This was the tactic used on the
Spitfire, if I remember....
There's another mass that is not structural like surface balances.

That's called a bobweight, and it's to give the pilot some sense of
the stress he's putting on the airframe. Many current aircraft use it.
Even the Cessna 185, IIRC, has it. See a service bulletin regarding
the bobweight on the Citation:
http://www.tc.gc.ca/CIVILaviation/ce...rt/1999-05.htm

Dan

On Apr 19, 7:55*pm, wrote:
See a service bulletin regarding
the bobweight on the Citation:
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Dear Dan,

On the Citation I believe you will find it is called the 'Robert
Mass'.

:-)