Going a bit overgross

[AndyFromCB]

Hello,

As soon new to be owner of a M20M, I have a question to all who have flown a Bravo. Let's see, M20K 2900lb/210hp equals to 13.8lb/hp. 270hp * 13.8 = 3728lb.  I'm fully aware that sounds alike a lot, but TAT A36 does 4000lb on 300hp, a Lance I used to fly had a 3600lb gross weight and I know many times where it was 200lb overgross with 6 big guys and full fuel in it.

I performed W&B and center of gravity wise, it's fine. We all know the spar and the tail won't even notice the difference.

So hypethically speaking, how is the bravo at about 200lb overgross on take off? I assume one could hardly tell the difference?

[Parker_Woodruff]

It'll fly - I know people who've done it.  I never said it was legal or that it was a good idea.  Someone at Mooney said they flew it at 4000lbs in flight testing.

Those wing fuel tanks might not be happy with the extra weight.

[AndyFromCB]

When you're refering to wing tanks, I assume you mean landing loads. What if one was always under the 3200 limit for landings? In my situation, it would require 30 gallons or less in the tanks with full TKS tank?

[Parker_Woodruff]

No.  Your fuel tanks are "wet wings".  That means that the aluminum tanks are sealed up from the rest of the wing (and outside elements) by sealant.  When you apply excessive loads or impact forces to the wings (via landing gear in this case), you are putting a lot of pressure on that sealant in different directions.  The sealant will eventually come apart in small amounts and cause small fuel tank leaks.  Some are airworthy, some require sealant patchwork.

Heavier Mooneys have always been more prone to premature fuel tank leaks.

[Shadrach]

I think it is a bad idea for obvious reasons, but I reject the notion the tanks would be more stressed or more prone to breach. The airframe is designed and tested to withstand loads far beyond that which would be encountered in XC trip. Is there any data to back up the notion that heavier planes are more prone to leaking? 

[PTK]

Along the general lines of this discussion, does anyone know what the difference is between the gross increase J vs the regular 2740 gross? Is it strictky paperwork or is there something structural as well?

[John Pleisse]

Quote: allsmiles

Along the general lines of this discussion, does anyone know what the difference is between the gross increase J vs the regular 2740 gross? Is it strictky paperwork or is there something structural as well?

[PTK]

Quote: N4352H

 Paperwork and a new airspeed indicator. Why? I don't know, perhaps different reference lines.

[John Pleisse]

Quote: Parker_Woodruff

No.  Your fuel tanks are "wet wings".  That means that the aluminum tanks are sealed up from the rest of the wing (and outside elements) by sealant.  When you apply excessive loads or impact forces to the wings (via landing gear in this case), you are putting a lot of pressure on that sealant in different directions.  The sealant will eventually come apart in small amounts and cause small fuel tank leaks.  Some are airworthy, some require sealant patchwork.

Heavier Mooneys have always been more prone to premature fuel tank leaks.

[AndyFromCB]

Well,

On a J, it's different tube thickness in the fuselage. That's why it only applies to certain serial numbers.

Andy

[John Pleisse]

Quote: allsmiles

 Paperwork and a new airspeed indicator. Why? I don't know, perhaps different reference lines.

[jetdriven]

Different tube thickness or marketing ploy to keep older airframes from having a 1200 LB useful load? Thats the first I heard of different tube thickness.

[John Pleisse]

Quote: jetdriven

Different tube thickness or marketing ploy to keep older airframes from having a 1200 LB useful load? Thats the first I heard of different tube thickness.

[Parker_Woodruff]

Quote: Shadrach

I think it is a bad idea for obvious reasons, but I reject the notion the tanks would be more stressed or more prone to breach. The airframe is designed and tested to withstand loads far beyond that which would be encountered in XC trip. Is there any data to back up the notion that heavier planes are more prone to leaking? 

[jetdriven]

the parts catalog does not show a different part number break at 24-1676 for the fuselage or landing gear components.

[Piloto]

I have ferried the M20M at 300+ pounds overgross and never found problems with it except may be on taxing. The plane will climb and achieve FL 200 with no major degradation on climb performance. It will take a longer run on takeoff but with a positive rotation. DO NOT TAXI ON GRASS at gross weight. The nose wheel can easily get stuck. The Ovation also has good performance at overgross. However on the M20J you can tell the difference at overgross (200lb) once you pass 6000ft, it becomes a slow climber.

José

 

[KSMooniac]

Quote: astelmaszek

Well,

On a J, it's different tube thickness in the fuselage. That's why it only applies to certain serial numbers.

Andy

[fantom]

Quote: KSMooniac

[jetdriven]

You could land it 1000 lb overgross but it better be smooth and of course the approach speed is higher.

[jetdriven]

This guy flew around the world in his M20J in 204 hours.  No weight given, but he mentions 20%, so that would be ~600 Lb.     from :  http://www.priortrip.com/

 

14) An airplane can successfully handle surprisingly more weight than I had been led to believe. While hardly good routine practice, ferry pilots will tell you, and I can now concur, that 20% or more overgross operation is quite possible safely. (You need an appropriate FAA sign off and Ferry Permit, plus a thorough briefing from a seasoned ferry pilot first!) Climb rate is obviously the most adversely impacted performance parameter, but after struggling up to cruise altitude, the Mooney flew only 7 - 10 knots slower than at normal gross weight. This speed penalty declined as fuel was burned over time. Adding this extra fuel weight near the aft CG limit helped a little, as the resulting reduced aerodynamic downward force on the tail in trimmed level flight partially offset the added weight. Needless to say, pitch stability suffered, though, and I had to fight phugoid oscillations for the first couple hours of each fully fuelled flight. Terrain and manmade obstacles near the departure airports became of paramount importance, as initial climb rates were an anemic 200 - 300 fpm maximum. As was first suggested to me by Barry Andrews when he and I visited the airport at Johor Bahru, Malaysia, the best way to get good information about local terrain and obstacles along a proposed departure path was to visit the local ATC Tower and get a briefing on suggested climbout routes. Outside the US where security is far less restrictive, I was routinely able to do this with minimal fuss as long as I wore my uniform and carried a pilot picture ID. Tower controllers were universally cordial and helpful, and the view from their elevated tower cabs provided a good preparation for the overgross takeoff.

[AndyFromCB]

Basically, my mission profile calls for between 3% to 5% overgross on take off, zero on landing. In a Bravo, it should be a non-event from what I gathered. Most older airplanes are usually 50 to 100 heavier than what the W&B says vs putting the airplane on the scale anyways. I know that because I've seen so many "less than 1lb, no W&B" entries from mechanics it's almost funny. Funny thing is if Mooney would have just for once in its company's life hired an engineer (that's a problem with a lot of american and european companies, too many lawyers around not enough engineers), all it had to do what put some vortex generators on a bravo and redesign the gear a bit and it could have created a full fuel and 4 seats bravo and it would still be in business. Oh yeah, and not dropped the TBM design...

[N33GG]

Quote: fantom

Carol Ann Garrett took off on both her around the world trips at 1,000 lbs. over gross in her 1990 J, and IIRC all it took was paperwork, a new W&B, and FAA approval. A return to land or an abort would have been bad, real bad.

[KSMooniac]

Quote: astelmaszek

Funny thing is if Mooney would have just for once in its company's life hired an engineer (that's a problem with a lot of american and european companies, too many lawyers around not enough engineers), all it had to do what put some vortex generators on a bravo and redesign the gear a bit and it could have created a full fuel and 4 seats bravo and it would still be in business. Oh yeah, and not dropped the TBM design...

[jetdriven]

Lynyrd Skynyrd's crash was never solved.  The aircraft ran out of fuel, but the closest theory they could determine was the right engine had a bad mag, and the crew ran it in auto-rich to cover up the rough running.  Convair 240 N55VM did not have a fuel dump switch, either.

http://www.check-six.com/Crash_Sites/LynyrdSkynyrd-N55VM.htm

[fantom]

Quote: N6719N