PA31 Guru Required

[Sweet Surrender]

After many years flying other types, I find myself back flying little (-310) Navajo’s. There have been a number of changes to Navajo's over the years, including the change in AFM’s and I am finding it difficult to obtain information.
I am flying two Navajo’s, both have vortex generator kits, one has 40° of flap the other 25°. One has wing lockers the other does not.

Questions.

Despite the different flap settings the short field approach speed and landing distances required appear to be the same. Is this correct.

The vortex generator supplement has two take off charts. STOL with 15° flap and normal with 0° flap. The Navajo without wing lockers has a 50’ speed on the normal takeoff (without flap) less than the 50’ speed on the STOL takeoff with 15° flap. ??

Any comments (regarding Navajo’s) gratefully received.

[Checkboard]

There are some PA31 operating tips on the PA31 Drivers (http://www.pprune.org/forums/showthread.php?s=&threadid=22424) thread in Dunnunder.

[Dale Harris]

The extra 15 deg doesn't lower the stall speed on PA 31's. The diff between flaps up and full flap is only about 4 kts anyway. The difference between having 25 deg and 40 deg is via a piper modification, that was required to overcome an assymetric flap problem that appeared. All PA 31's have the ability to apply 40 deg of flap, it's just that unless the AD's are accomplished, the flaps are required to be mechanically limited to 25 deg, which allows some control of the aircraft in that situation. And it is marginal control at that, hence the max of 25 deg. The differences in speeds etcetera wing lockers and sans winglockers are due to drag considerations and single engine speeds I think. Welcome back to 'em, they not that bad..............

While we're at it check the VG kit manufacturers AFM supplement. If you get to fly the -350, MCP goes from full throttle and 2575 RPM, to 40" and 2400 RPM. The old MCP has a 5 minute limit applied to it after fitment of the kit. Dunno if it affects the -310 tho.

[Sweet Surrender]

Thanks guys for your reply's.

When I first flew the PA31 I was taught to lean it out on EGT's.

The next time round I have been taught to set fuel flows and monitor EGT's.

The latter is quicker but I feel happier doing the former.

What is the normal procedure out there in Navajo land?

[Dale Harris]

Big bone of contention at the moment SS. It is possible for both methods to do damage, especially if instruments are not within calibration. There is a couple of threads around dealing with this. If you'd like to email me again about it, I can point you in a couple of directions if you like..........

[GoneWest]

Dale - would you mind continuing your conversation on line - rather than via e-mail??

I'm watching and revising my PA31 handling tactics as well.