Circuit breaker tripping

You need a clamp on A/C ammeter (I have 2)

True story (with built in hint) on my Coach one of the A/Cs started tripping it's branch breaker (i'm on shore power) Clamped on and confirmed amps were climbing, NOT a breaker problem (20 amp breaker tripped at 21 amps)

Removed outer and inner covers.. Took a look at the Condenser coils,, Said "YUCK" blew and brushed the crud out. and did a general cleaning while I was up and about.. Have not tripped a breaker since (This was last year).

The OP said "one of two" breakers are tripping. This leads me to believe he means the two main service leg breakers. My 5500 has two breakers located on the generator. If one of these is tripping, he has a short in that leg or some other overload. I guess we'll not know until he re-posts the answer.

The OP stated that the breakers trip with on-board genset and a portable genset. That should eliminate issues with the ATS.
OP:
What breakers are tripping?
Are they on different legs of the 50 amp service?

How many amps before tripping is a clue. An analog ammeter samples instantly and if for instance it surges to 70 that's a great clue. A post generator fault line to neutral could do this.

Stop all power. Throw breakers and yank plugs. All of them in the rig.

Using an ohm meter on lowest scale start probing outlets neutral to hot. What did you find?

cannot stay conneccted to shore power
what ever is going on is in the RV house circuits

suspects
water heater electric heating element
fridge heating element
charger/converter ( can be combo inverter/converter )

look at which breakers are tripping and what is on the circuit
IF it is your main hose breaker
then you could have a problem with the "automatic transfer switch"
usually referred too as the "ATS", big relay that switches between shore power and generator
loose connections or stuck contacts, in there can cause the house main to trip

Like Old-Biscuit says, first rule of troubleshooting, ask yourself "what is not working" and work backwards from those items. The circuit breaker can be tripping from something as simple as a loose wire connection. I say simple but if fact these can very hard to find.

Most of your 120v is for outlets or heating elements. If your tripping a breaker at the gen-set you'll have a large search area. For a gen-set breaker try turning off all breakers in the panel. Gen-set should run fine. Then one by one turn on a breaker, start with the mains. When you trip the breaker you've found the circuit with the problem (not saying you can't have more than one). Now you have to check everything on that circuit. Don't forget to check the wiring connections on the back side of the breakers.

If it's a panel breaker this helps narrow down your search. A 50 amp system can just be one side which helps eliminate half of your system. Of course a system breaker like for a AC unit will require checking out that particular appliance.

For outlets, a quick visual look at each outlet for a scorched spot or maybe it will smell burnt. I have replaced several bad GFCI outlets. Check things systematically, start with the outlet farthest from the box and work back. With the breaker off (CHECK WITH A METER THAT NO POWER IS PRESENT) pull out the outlet and check for loose wires, scorched spot, melted plastic etc.

Average problems take more time to find than to fix. I hope this makes sense and is at least as clear as mud. Good luck and be safe.

Without more information, it is hard to tell.
I would check the neutral connections in the 120/240 volt power distribution panel.
Get some electrical de-oxidation grease before you start.
Disconnect from AC power source.
Remove cover from AC power distribution panel.
Look in the back of the box for where the neutrals connect. (white wires)
Disconnect each one on at a time. Clean the buss bar and wire. Cut it back if it is real bad.
Apply a liberal amount of de-ox compound and re-terminate.

Same as always, getting info like pullin teeth

Know which circuit breaker that is tripping may help.

What is on the 'circuit' that is tripping......what stops working?

Same problem using a different gen so issue is NOT with gen....it is something in MH

What size circuit breaker is tripping?

Fridge electric element
Water heater electric element
A/C Unit Fan motor...compressor motor
Converter
Microwave
ANY 120V Lighting
ANY Items plugged into an outlet

When CB trips something AC stops working???????