Is power-line patrol a part 91 operation? got some loon telling us that a 133 or 135 cert is needed. Not picking anyone up from point A and dropping off at point B, nobody and nothing is dangling beneath us from a string. 

You are being paid with co-workers on your manifest, so it's Part 135.  But when you dumb off those co-workers and return to base solo you are now Part 91.  

Out. Now some of the equipment used to replace worn or missing parts on the line could be considered cargo for delivery.

first of all a manifest is only required for multi engine aircraft on a 135. So this has nothing to do with making a flight 135. 

135 is for point A-point B transfer. not powerlin work as described in 119.1. Seems out industry has failed us alll a hit of regulation.

If you are a company hired by another company to conduct those patrols, then it likely 135 because you are holding out to the public to fly air commerce.

If you are conducting those patrols for your own company, it can be done Part 91, but the pilot needs a Commercial ticket if he is being paid as a pilot.

If your company contracts with another company privately, and not with others, then it can be considered a private conveyance and done under a Part 91 Operators Specification, but it will need to be FAA (FSDO) endorsed.

 Power line patrol falls under part 91 and guess what you can drop someone off at a different location than you picked them up from. It's a patrol flight for money not a point a to point b for money.

are wrong.

Amazing to me how few understand this regulation. Read 119.1 

While patrol does fall under Part 91, as it is specifically called out in Part 119 as an exception to the Part 135 rules, like most FAA topics- there are exceptions to the rule. 

I'd suggest the OP check out the FAA Office of Chief Counsel opinion website. There is something called "Dual Purpose," whereby the patrol flight can take on a dual purpose and become Part 135. See the Bonilla opinion.

No it can't take on 135 unless you are calling it a patrol flight and doing 135. You can legally do a patrol flight and drop the person off after 100 miles away as long as it's actually a patrol flight and that's what the dude is paying for

What you have provided is an example of a Dual Purpose flight. While you provided patrol services outbound, once you drop that crewmember, you have the provided transportation to that individual. 

Additionally, it doesn't matter what is being "paid for" or the operator chooses to classify the flight, "patrol" in your example. 

Finally, the FAA has provided the answer to this question via the Bonilla opinion referenced above. It only matters when they are notified. 

Where does it say the patrol flight must begin and end at the same location? Are you using the tour non sense with a loa that must begin and end at the same local?

It doesn't say the patrol flight has to begin and end at the same point, in fact the Chief Counsel interpretation above makes that clear. A patrol flight can go cross- country, across multiple states. The legal issue if the FAA found out, comes when you drop a crewmember (you've provided transportation).

The FAA has provided examples of what would make the patrol flight take on a Dual Purpose. Some of them are fairly innocent seeming and were eye opening. 

Tailwinds~

be careful about sectors of third party personnel carriage with no active patrol being undertaken.

Patrolling lines doesnt make you a Powerline pilot. You earn that feather in your cap once you do a center phase hot full tension splice.

happens if the engine or tail rotor fails?

Its part 91.  I'm on the HAI UPAC working group.  Take a look at all the operators doing powerline work then look up how many have a 135 certificates(almost none) The FAA sends reps to our meetings and never has the issue of needing a 135 certificate come up.

If you're having problems with the FAA, call HAI and ask to talk to Chris Marino, they always want to know when FSDO are coming up with different interpretations of the regs.

Now, the fact that you're asking makes it sound like you guys are new and trying to break in to the work.  Please read/apply the UPAC guide, get some help setting up your program and get some professional training for both pilots and inspectors on flying in the wire environment.

Good luck.