Author Topic: H-700 cowling modification to improve cooling  (Read 411 times)


H-700 cowling modification to improve cooling
« on: December 29, 2020, 10:47:25 PM »
I have read a few opinions of the H-700 requiring rich power settings to cool the engine and wonder if anyone has experimented with cowling modifications to correct the heating problem ?



Re: H-700 cowling modification to improve cooling
« Reply #1 on: December 30, 2020, 09:42:17 AM »
Yes it was done.  By Mr Casper, ( i think that was the name of this fine gentleman, please correct me someone)

He did work a lot on a modifies cowling of the 700, and even the 800.  He also STC'd and invented a landing gear made out of a solid piece of aluminum to replace the composite gear.

It was a little more easier to land ( less spring than the composite).  At the time of the 700 and 800, i think the guy in charge came from Cessna.  So he did replace the soft energy absorbing landing gear of the real Helio with a springy composite legs, and remove the shock absorber inside the frame.  So it would land like a 185.  Changing also the angle of attack at take-off and landing to a more flat one, just to be sure to make almost impossible smooth landings with those fixed springy legs.  The composite or the aluminium legs were very strong compare to original design.  So strong that when the s*?# hit the fan, the legs would brake the frame where they were attached, or the other end at the wheel axel.  But the legs were still serviceable.  It was the frame that was no more.

Been there, done that.  With my 800.  Once on the wheel end in the mud, once on the frame end on a island of sand in Iceland.

« Last Edit: December 30, 2020, 09:52:11 AM by Louis »

Doug Johnson

Re: H-700 cowling modification to improve cooling
« Reply #2 on: December 30, 2020, 01:11:05 PM »
I thought Clarence Brent did all the enineering for the aluminum gear legs and the I'm pretty sure Clarence Brent improved the cowling for the O-720 in the H-800, H-5.

You can find the STC SA2141CE and pictures of the cowling for the H-700 c/n, H-7 as 5B-CIH here

I havent checked for about 7 years but H-7 with the modified cowling may still be among the bunch of aircraft removed from service in Cypress in a lot near the control tower

this is what you find when you look up the STC
SA2141CE,"Wiplinger Robert",Reissued,07/05/1990,"Wipaire, Inc. 8520 River Road","Inver Grove Heights","MN","55076","United States","Replacement of engine cowl and baffles.","1A8,","ACE-115C Chicago Aircraft Certification Office Tel: (847) 294-7358","Alliance Aircraft Group, LLC\H-700

My understanding is that Wipaire is not really interested in making a cowling for you and if you were able to talk them into it the cost would be astronomical.

Take a look at the cowling at the link above its possible that with the assistance of an engineer with engine cooling expertice and a fiberglass shop you could do a one time STC and build your own or Wipaire might sell you a copy of the STC so you can build your own
« Last Edit: January 03, 2021, 09:22:05 AM by Doug Johnson »


Re: H-700 cowling modification to improve cooling
« Reply #3 on: December 31, 2020, 09:46:43 PM »
Hello Doug and Louis,
Thank you VERY MUCH for the info. This site is a great help due to input from people like you.
This kind of info is very valuable.


Re: H-700 cowling modification to improve cooling
« Reply #4 on: January 04, 2021, 05:57:45 PM »
Doug, I've been watching this H-700 cowling discussion for some time and finally decided to do a map look. I'd love to get that cowling for our H-700 (along with the STC...) but Cyprus is a bit out of the way. The airport in the attached photo is not Lakatima, which I think was abandoned before H-7 got over there, but Larnaca, currently in operation and serves Nicosia. Whether H-7 is one of the planes in the photo is another question but, at least as of the date of the mapping photo, there was still a yard with what look like abandoned small aircraft with one or two that could be a Helio.