Updating AD 69-24-04 (Vmc increase) PA-30?

[Marc Arsenault]

Hello All,

Has anyone thought about having the FAA review and certainly ask them to consider modern human factor technology regarding AD 69-24-04 (Vmc increase)? Airworthiness directives as you know are regularly revised when new technology improvements are made available ie for "mechanical type AD's. It would appear that cancellation of AD 69-24-04 would be a very economical update and be very beneficial to the community of pilot/operators.

The 78 kt Vmc grieved upon the PA-30 back in the late 60's was perhaps justified. Training techniques and human factors were not even close to what science has provided to the industry over the last 5 decades. The aircraft as we know, does not demonstrate any "handling vice" that justifies such drastic performance adjustments.

Certainly, over the years, the paradigm has been set and we have all been accustomed to it, not wishing any heavy administrative dealings on the issue.

A return to original Piper figures appears to be a very simple and cost effective correction to apply. There would be some AFM amendments about minimum altitudes for stall training and single engine demonstrations.

But then, perhaps the issue has been tackled previously. I have not read or found any documents to the effect.

Thoughts and ideas are welcome !

Regards

Marc Arsenault
C-GDSY
CZBM

=======================
FAA
69-24-04 PIPER: Amendment 39-878 as amended by amendment 39-896 is further amended by Amendment 39-2991. Applies to Piper PA-30 type airplanes certificated in all categories except aircraft incorporating Piper Kit No. 760 368.

Compliance required before further flight, unless already accomplished, as follows:

Change the existing Vmc placard to state the following:

"Minimum Single Engine Control Speed 90 mph CAS".

(Piper Service Bulletin 301A (http://www.webcoaircraft.com/sb/sb301a.pdf) dated November 25, 1969 pertains to this subject.)

Amendment 39-878 was effective November 27, 1969.

Amendment 39-896 was effective December 26, 1969.

This Amendment 39-2991 is effective August 5, 1977.

[Eric Jessen]

[Marc Arsenault]

Thanks for your message Eric,
The effect on performance would first permit a shorter accelerate-stop distance. This number is more restrictive ie longer than the actual take-off distance. One can chose to ignore it I suppose since the aircraft has no tendency to lead to a loss of control past 69 kt. Also the best angle climb speed (Vx) and best angle climb speed single engine (Vxse) would both be reduced, allowing for a shorter take-off speed over a 50’ obstacle.
Regards
Marc

[Eric Jessen]

I was not aware that they changed the Vx speeds along with the Vmc. That said, if you know what the old Vx numbers are, who's to stop you from using them? I would practice short field TOs using both Vx numbers though to see if there is any appreciable difference in altitude gained. I personally would not fly into an airfield where I needed the extra performance. I have a PA-12 for that .

[Marc Arsenault]

The PA-12 is a cool machine indeed. Tail draggers as far as I am concerned are the best aircraft to enjoy bare flying. Not a single dull landing. Many hours on a 150 hp PA-20 and PA-18. My dad flew years ago a PA-16.

As far as PA-30 is concerned I would not want to operate some form of STOL concept into marginal field. Yet the idea that there would be quite an improvement on "legalities" as far as performance is concerned is a major plus. A gentlemen wrote some time ago that the PA-30 was indeed a 69 kt Vmc machine (which it is) and operates it accordingly. Probably most people do. I am not totally confortable with to fly not by the book. Flight discipline obliges.

The AD was issued with a simple stroke of a pen by an FAA executive that had no concept of human factors back in 1972. This was not his fault nor anyone else then, this was merely the state of the science. I figure it is time to correct this clerical issue without any major effort or cost, those being really minimal. This would certainly equate to performance enhancement and appropriately add well deserved value to our birds.

Best regards

Marc