PDA

View Full Version : Increasing Max gross weight



ov1guy
11-09-2011, 07:28 PM
Greetings. Somewhere I saw advice on how to increase the max gross weight of a experimental aircraft. I cannot find it now. If I remember, it really was just a notification of the local FAA and a logbook enttry. But the advice I saw had specific wording and I sure would like to see that advice again. Any one know where I can find it?
Bob

Snowflake
11-10-2011, 08:02 AM
Don't forget the structural analysis of the aircraft to ensure that it can actually fly safely with the increased load.

Dave Prizio
11-10-2011, 11:10 AM
A gross weight increase is a major modification. To proceed with a major modification you should first look to your operating limitations for a description of how such a thing should be handled. As a general rule you will need to make a logbook entry stating the new gross weight, talk to your local FSDO about your modification, re-enter Phase I flight testing for 5 hours (or whatever the FSDO requires), perform your flight tests, and then make a second logbook entry noting completion of the flight test period.

You should also have some good engineering justification for increasing your gross weight, but there is no FAA requirement to prove that your gross weight increase is sound from an engineering standpoint. It is your decision to make, for better or worse.

I suggest you read Dick Van Grunsven's article, "At What Price" in the August 2011 issue of Sport Aviation before you make your final decision.

Dave Prizio

Thomas Stute
11-13-2011, 04:55 AM
Don't forget that increasing the gross weight is an engineering task. Before doing any of the steps proposed by Dave justify with the structural analysis which gross weight increase you want to achieve and check the remaining margins of safety. If everything is fine here check the analysis of the longitudinal control wrt allowable range of CoG. If eveything is still OK proceed as Dave Pririo wrote.