Open the Eagle Scout Project Workbook (opens PDF file) and you will find about 2 1/2 half pages of instructions about conducting the project written in less than 1000 words (966 to be exact).
Google the words "Eagle Scout Project" and you'll get about 1.4 million references.
Avoid drama by reading only the 966 words in the workbook. If you think this is adequate advice stop reading now and move on. Otherwise you can continue reading as I, unfortunately, add to the vast commentaries on the Eagle project out of necessity in the hopes that it will help someone avoid some drama.
If your Council Advancement Committee has amended the workbook (as mine has) get a clean copy of the current workbook from the link above. Check the National Eagle Scout Association site to be sure you have the correct iteration of the workbook (this is important). If, along the way, someone like your District Advancement Chairman insists on something outside of these 966 words insist (politely) that they show you in black and white the language from the BSA (not the Council Advancement Committee) upon which their instruction is based.
If it is not in the workbook it is not part of the requirement. I am writing principally on the administrative aspects of the project because the candidate themselves take care of the execution of the project and, ideally, no adult leaders from their Troop are involved in that phase of the project.
Here's the things that usually cause problems;
A perennial observation of Scoutmasters and other leaders is that Scouts seem to be doing similar projects over and over again. This must be a very common concern because the BSA has chosen to address it specifically.
Does the leadership service project for Eagle have to be original, perhaps something you dream up that has never been done before? The answer: No, but it certainly could be. You may pick a project that has been done before, but you must accept responsibility for planning, directing, and following through to its successful completion.
There is a clear answer to the question of originality - NO. Anyone who insists on originality is adding to the requirement which, we all know, is a big no-no. Remember that you may have seen a dozen Eagle projects that were very similar or exactly alike - but it is all new to the Eagle candidate.
No minimum number of hours is required
A simple statement - need I explain it? No 'target number of hours', 'average number of hours'. If stating these were important or helpful don't you think that the folks at the BSA who have seen two million Eagle Scouts would have included them?
There are no specific requirements. Nada, none, no, not any.
How big a project is required? There are no specific requirements, as long as the project is helpful to a religious institution, school, or community. The amount of time spent by you in planning your project and the actual working time spent in carrying out the project should be as much as is necessary for you to demonstrate your leadership of others.
It is up to the Eagle candidate to design his project to adequately demonstrate his abilities.
The Scoutmaster's Role
Scoutmasters approve the project plan and may have a role in helping advise and coach the Scout as through the planning process. Sometimes Troops have an adult leader who is detailed to do this.
An Eagle Candidate is conducting his project to demonstrate his leadership of others. Who will ultimately pass judgment on whether or not he has done so? Not his Scoutmaster. The Scoutmaster signs off to certify the project "was planned, developed, and carried out by the candidate", not on the quality of the project or the leadership, this is not the Scoutmaster's concern. The Board of Review, and they alone, will evaluate this aspect of the project.
Eagle projects may be simple, complex require thousands of dollars or not one cent. They may take months or days to complete and require tens or hundreds of hours on the part of a few people or a veritable army of helpers. They may have a tremendous impact or simply make a difference. Every project in this broad spectrum is valuable, laudable and important. There are few, if any, universal standards to the size, scope and originality of the project so every Scout, regardless of where he lives, his talents abilities or resources has the opportunity to become an Eagle Scout.
I readily guide Scouts to explore what others have done for projects and encourage them to be imaginative and expansive when planning their projects. But I guard that my encouragements did not become so coercive to be thought of as a requirement.