Static RPM in '74 Archer?

[Bob Chilcoat]

My partners and I have all noticed that takeoff roll and climb in our Archer
is a bit long and anemic, respectively. The partner who has had a share the
longest has said that normal TO RPM has always been around 2,250. One of us
recently flew a Cherokee 180 (same engine) that climbed much better and got
over 2,500 RPM during TO. We have roughly 1,500 SMOH on the engine, and
compressions are all in the 70's. Someone on the Piper group suggested that
the muffler might be plugged. The POH says nothing about normal static RPM.
Any thoughts?

--
Bob (Chief Pilot, White Knuckle Airways)

[mikem]

Take a small rubber mallet, and gently rap on the muffler. If there is
anything loose inside, then its time to take it off and look inside.
MikeM


On Fri, 15 Aug 2003 09:18:12 -0400, "Bob Chilcoat"
> wrote:

>My partners and I have all noticed that takeoff roll and climb in our Archer
>is a bit long and anemic, respectively. The partner who has had a share the
>longest has said that normal TO RPM has always been around 2,250. One of us
>recently flew a Cherokee 180 (same engine) that climbed much better and got
>over 2,500 RPM during TO. We have roughly 1,500 SMOH on the engine, and
>compressions are all in the 70's. Someone on the Piper group suggested that
>the muffler might be plugged. The POH says nothing about normal static RPM.
>Any thoughts?

[[email protected]]

"Bob Chilcoat" > wrote in message >...
> My partners and I have all noticed that takeoff roll and climb in our Archer
> is a bit long and anemic, respectively. The partner who has had a share the
> longest has said that normal TO RPM has always been around 2,250. One of us
> recently flew a Cherokee 180 (same engine) that climbed much better and got
> over 2,500 RPM during TO. We have roughly 1,500 SMOH on the engine, and
> compressions are all in the 70's. Someone on the Piper group suggested that
> the muffler might be plugged. The POH says nothing about normal static RPM.
> Any thoughts?

copied from:

TYPE CERTIFICATE DATA SHEET NO. 2A13

This data sheet, which is a part of Type Certificate 2A13, prescribes
conditions and limitations under which the product for which the type
certificate was issued meets the airworthiness requirements of the
Federal Aviation Regulations.

snip

XII - Model PA-28-180 (Archer), 4 PCLM (Normal Category), 2 PCLM
(Utility Category), Approved May 22, 1972, for S/N 28-E13. and
28-7305001 through 28-7505260.

This series differs from the basic PA-28-180 (Item III) by the
addition of a five inch fuselage extension, wing span increase larger
horizontal tail, gross weight increase and other minor changes.

snip

Propeller and Propeller Limits

Sensenich or 76EM8S5 or M76EMMS
Static r.p.m. at maximum permissible throttle setting not over 2425
r.p.m., not under 2325 r.p.m.
No additional tolerance permitted.
Diameter: Not over or under 76".


Apology implied if cut-and-paste format is messed up.

Regards;

TC

[[email protected]]

On 15-Aug-2003, Tim Bengtson > wrote:

> I have had the same symptoms for two different problems. One, as has
> been suggested, was a blocked muffer. Bang the thing around a little
> bit and see if anything rattles in there.


Some other possibilities that are easy to check it static RPM is low:

1. Verify that the throttle linkage allows the throttle to be fully opened
with the control full forward.

2. Verify that the carb heat shuts off completely.

3. Check to see if leaning the mixture increases static RPM. Of course, it
will if the test is done at a relatively high density altitude, but if RPMs
increase with leaning at or near sea level the full rich setting is probably
too rich, or else there is an obstruction in the induction air system (e.g.
a clogged air filter).

Let us know what you find out.

-Elliott Drucker

[Snowbird]

"Bob Chilcoat" > wrote in message >...
> My partners and I have all noticed that takeoff roll and climb in our Archer
> is a bit long and anemic, respectively. The partner who has had a share the
> longest has said that normal TO RPM has always been around 2,250.

Before you get too concerned that the engine is a problem,
have you had the tach checked recently? There's a program on
the internet which will do this by recording a sound file and
analyzing it with the program -- google search for it if
interested. Otherwise find someone w/ an electronic tach
checker.

It's pretty common for an older mechanical tach to be off
by 100 or even 200 rpm. Often it's high, but low is not
unheard of (ours as it happens is low)

Not to say that something isn't amiss, but make sure you've
identified the problem first?

> One of us
> recently flew a Cherokee 180 (same engine) that climbed much better and got
> over 2,500 RPM during TO.

The other issue is whether the two planes have the same prop, and
were they at the same max gross weight and comparable DA when
comparing them?

Cheers,
Sydney

[Snowbird]

"Bob Chilcoat" > wrote in message >...
> My partners and I have all noticed that takeoff roll and climb in our Archer
> is a bit long and anemic, respectively. The partner who has had a share the
> longest has said that normal TO RPM has always been around 2,250. One of us
> recently flew a Cherokee 180 (same engine) that climbed much better and got
> over 2,500 RPM during TO. We have roughly 1,500 SMOH on the engine, and
> compressions are all in the 70's. Someone on the Piper group suggested that
> the muffler might be plugged. The POH says nothing about normal static RPM.
> Any thoughts?

Whups, hit send too soon on my other post.

My thought which I haven't heard mentioned elsewhere is, check
and double check the carb heat to be sure it's really OFF when
the control is in the off position. A worn carb heat actuator
arm or valve which isn't really quite seated "closed" can easily
cost you 100 rpm.

Cheers,
Sydney