Avstar Aircraft of Washington, Inc.

10415 172nd St. E., Hangar A1
Puyallup, WA  98374
office (253)770-9964
or (253)770-0120
email:  avstarair@att.net

12-01-1999 Ask Mike! Archive
Can I get gross weight bonuses when upgrading?

Dear Mike:
I've been considering some upgrades to my V35 Bonanza.  By looking over my wish list, I find I can actually get gross weight increases with some of them.  In fact, I should be able to up the gross on the old girl by 300 pounds!  In the sacrifice of, say 50 to 75 pounds of equipment, I net well over 200 pounds useful!  Seems pretty cool to me.  Why aren't these things advertised more?


Most sellers of aftermarket alterations that affect aircraft performance (horsepower increases, aerodynamic alterations, etc.) only casually mention the POTENTIAL for a gross weight increase.  Why?  The best answer for this is found in your aircraft paperwork (logbook) file. Chances are you already have one form or another of a Supplemental Type Certificate (STC) already installed on your airplane.  Pull the official STC document from your file and read it.  There is a paragraph on it that reads, in part, "The compatibility of this design change with previously approved modifications must be determined..."  Also, when you look at the GWI, consider the paperwork officially gives you a new gross weight number.  In essence, if your V35 flight manual gives a max. weight of 3400 pounds, and you convert to an IO-550, there is paperwork to get your new max. weight to 3500 pounds.  (A 100 pound increase.)  If you add tip tanks, the accompanying paperwork may allow a max. weight of 3600 pounds.  (A 200 pound increase.)  Provided all other qualifications are met, you can only take the highest GWI.  They are not additive. Incidentally, on some tip-tank installations, the additional weight might only be useable as fuel in the tanks.  These are not pitfalls, just areas to watch and consider prior to investing.
Gear green,