Cover letters
A couple of ideas before I share the text of what I used.
First of all, get the pilot recruiter's name. Don't send a letter to "Pilot Recruiting." It looks and sounds tacky. Just call the company and ask for the name of the recruiter.
Another point is you can use some standard form and language, but know the company and try to customize it so it sounds more personal.
While I'm on the "personal" kick, keep your letter brief; the reason being that the only people who review cover letters are H.R., who lack appreciation for the effort you put in to them. Unfortunately, the higher-ups, to whom you could sell quals and outstanding personal traits, don't see these letters. Just H.R., who are really only interested if your quals match their profile.
Finally, don't rehash your resume. Just showcase the quals you have that they want. Probably that will be total time, multiengine, pilot certificate and medical. You primarily want to point out that your credentials meet or exceed their quals.
Having said all that, try something like this:
Your address
City, State, Zip
email
Date
Joe Blow, Pilot Recruitment
XYZ Airlines
100 Main Street
City, State, Zip
Dear Mr. Blow:
I should like to apply for a Flight Officer position with XYZ Airlines. Enclosed is my resume.
My qualifications include 4565 total hours, 1380 multiengine, an Airline Transport Pilot Certificate, a First Class Medical Certificate, and a four-year college degree. Currently, I am flying as Captain on the KingAir 350 for Joe's Flying Service, an FAR Part 135 operator. I fly an average of 60 hours a month. I also free-lance flight instruct on weekends and teach Private ground school at Smalltime Vo-Tech.
I have always regarded XYZ Airlines as one of the top commuter airlines. I read recently in the Podunk Rag that XYZ will be expanding its operations during the next year. These plans sound very exciting and I am sure you would find my abilities and work ethic to be valuable.
I would very much appreciate the opportunity to present my qualifications to you in person. Thank you for your time and consideration, and I look forward to hearing from you.
Respectfully,
Flyby
Hope that helps. Good luck with your job search.