76" prop on a 180HP ***UPDATE***

[hilltop170]

Be careful with that MT reversible prop. I witnessed a Murphy Moose crash next to Merrill Field in Anchorage a few years ago when the MT prop on the Moose went into un-commanded reverse. It was making a normal approach until the prop reversed. At that point it descended rapidly until it hit in the Sam's Club parking lot and skidded to a stop in a dirt lot on its belly. Minor injuries but totalled the plane. I have never seen a single engine airplane descend that fast from a normal approach. The pilot said he gave it power to stop the descent and it just went down faster. He flew the plane all the way to the ground and flared as much as he could but it was not enough. Total landing distance was about 200'.

[n2582d]

From this thread http://www.supercub.org/phpbb2/viewtopi ... sc&start=0it sounds like it was an electric reversible prop rather than a hydraulic one on the Moose. I wonder why the safety features-squat switch or airspeed switch-didn't prevent that from happening.

Do you guys with the controllable pitch props go to low rpm/high pitch when simulating engine failures? It made a huge difference in glide ratio on the 3-bladed Helio Courier. Probably less so with a two-prop on the 170.

A cheaper option than a reversible prop was used by MAF on their 185s. They used a "rake brake" for emergency stops. This device was made from welded square tubing about a foot long and slightly wider that the tailwheel. Picture a mini ladder. It was mounted forward of the tailwheel, hinged at the aft end. The forward end of the rake brake was held in position by a solenoid-activated pin. When in looked like the end was near (of the runway that is) the pilot would press the switch to retract the pin and the rake brake would swing down below the tailwheel. The weight of the tail would aid in slowing the plane.

[Lopez]

UPDATE!!!

I've been working on this field approval for a while...basically since last August. To be fair, August through January delays were partially my fault.

Here is what I submitted:
-Copy of STC SA806CE from my records
-Copy of STC SA749CE from ???
-Cessna TCDS showing that Cessna used a 76" prop originally (to show ground clearance wasn't a problem)
-Hartzell prop TCDS showing that the 76" is approved on the engine

Seems like everything they might need...

Then I submitted a copy of the Hartzell STC for the 8477 prop, just to show that up to 80" was okay.

This morning the FAA man calls for clarification...I was a bit frustrated, since I've answered every question he's come up with. He's asking wjhy we need a field approval, since the prop is already specified in the STC? I tell him it isn't specified in the STC. He says yes it is, right in this paragraph. Then the light goes off! I ask what is the amendment date of the STC he is looking at? He says 1993. Mine is dated 1976. I download the latest copy of the STC from the FAA site and holy cow he's right!

So I learned something new. I'm usually very good at picking apart paperwork and finding these nuances. I've never had a case like this, where an STC was amended to add parts eligibility.

The end result is I'll install the prop with a logbook entry referencing the amended STC, and include a copy of the amended STC.

This airplane will be for sale soon! I bet you'd look good in it.

[tweiss]

Lopez,
Could you link the address to the 1993 update. Having difficulties finding it on the FAA website.
Thanks
Tom

Oh, disregard.
I think I found it!

http://www.airweb.faa.gov/Regulatory_an ... ht=sa806ce

Thanks for all your research anyway.
Tom