Diet plan for skymasters?

hharney · #1 10-12-17, 07:47 PM

Jim

I think you are asking for a lot with just avionics upgrades. Have you seen any W&B history for this plane? If there is any history this might clue you in to something that added a lot of weight at some point. With avionics update I would guess you might gain 20 or 25 lbs, that would be a lot.

There are lots of mistakes made in W&B calculations too. Look closely at the sheets

kilr4d · #2 10-12-17, 08:02 PM

Jim, it's not uncommon for people to ask if they should do an actual re-weigh or just go with a calculated W&B after work has been done.

The usual answer is to "prepare to lose some useful load." I've not seen a legacy GA aircraft yet that was as skinny as the factory weigh.

BTW, was your bird repainted? Paint is REALLY heavy if put on too thick. Also, I was very surprised how much my carpet and underpad weigh after 40 years of moisture, hydraulic fluid, etc.

Flyer770 · #3 10-12-17, 08:57 PM

I'm pretty sure Cessna, and most other GA manufacturers, never weighed planes on the line and instead based their numbers on a perfectly built theoretical plane. Add in years of rounding errors and absorption of fluids by fabric and insulation and it's not surprising that the theoretical and actual weights can differ.

JimC · #4 10-12-17, 09:33 PM

I gained about 60lb doing a major upgrade on my 340. One single box that wasn't even hooked up (old inverter) was 11lb by itself.

I'll going to ask for the history on this one. 250 over factory weight seems fat - I'm guessing I might find a typo. After my upgrade we did a reweigh, and I found a typo right away in the signed W&B that they put in my logs.

LostKiwi · #5 10-14-17, 07:15 AM

I'm big on "the diet" as well. Over the years my plane had a few different radios, ADF's and whatnot installed in it.

Its pretty common for shops to run new wiring and just cap the old stuff, rather than spend the time to remove the old wiring. I've done half of my insti panel, gutted as much of the old stuff as possible. Removed old ADF systems, DME and other stuff that can be replaced with modern gear, and literally a box full of wiring.

My (calculated) change was about 21 lbs.

If you really wanted to save weight, the obvious solution would be to ditch the vacuum system, and go to a DC and/or Glass install. Then 3 bladed props. Then... then... then...

There is no problem that cannot be solved with the correct application of money.

Leighton

n86121 · #6 10-14-17, 04:42 PM

I have a turbo T337D with RSTOL.

I eventually replaced my factory original RT485 radios (I think that was the number), when one of the gears broke.

Each original 'radio' was actually just a head, which then connected each to its own radio in the avionics bay, each of those having its own power supply. I don't remember the number, but that pile of stuff weighed a lot when it came out.

With the Robertson STOL (which I have) you also have heavier gross takeoff and landing weight available than stock, by quite a bit. Need to double check but my gross takeoff is something like 4700 lbs and a hair less for landing.

I think my empty gross around 3k as well. I don't worry about it because the RSTOL kit gives you so much payload, and rock n roll short field and climb performance, it's simply not an issue.

I took off near gross only once, years ago, out of my 2665 runway, deep in a valley, on a warm summer day: Two adults, two kids, a huge afghan dog, two violins a cello, enough tiles to redo all the entire counter tops in our beach house kitchen, two 'hanging baskets' 30 lbs of dirt w my wife's flowers), our luggage, and yes, like the joke says, everything INCLUDING the (new) kitchen sink. It was HEAVY, but fine.