Do small airports or regional airports with just a couple of flights per day, maybe even from different airlines all have on-site aircraft maintenance staff? It hardly seems economical to have certified on call mechanics at most small airport? Are there regulations requiring such?
If there are not any, what happens if a hard landing is performed? From my knowledge an inspection by a mechanic is then required.
For scheduled commercial aircraft you will generally find:
If enough aircraft are coming and going from a particular airport, the airline may keep a line maintenance operation running there that can handle short-term maintenance and troubleshooting, or special inspection operations.
If not, and the airport has a AMO (approved maintenance organization) on site, the airline may contract with the AMO for line maintenance services, troubleshooting or special inspections.
If that's not the case, the airline will simply fly mechanics to the airport when airplanes are AOG. This is typical when airplanes have problems that prevent dispatch at small remote airports.
So if an airplane needs a hard landing inspection at a remote "outstation", it'll be done by local contract staff if an AMO qualified to do the inspection is there, or barring that, airline staff flown out to the site.
In my experience you can often find an A&P at a lot of (but not all) airports even really small ones like KDYL where I learned to fly. However these mechanics may not have the experience or know how to work on all aircraft all the time but can likely handle most straight forward issues that could arise for the aircraft that land at the field. These mechanics may not work for the charter or airline operations based at the airport or elsewhere but are often more than capable of working on their aircraft provided the airline/charter operation permits it.
Keep in mind that at a great deal of airport there are at least a few aircraft based there (commercial or not) and all aircraft need at least an annual inspect so a mechanic is often never far off.
As others have said, airlines may have line-maintenance staff on-site, either organic or contracted through an AMO of their choice. On the GA/non-airline side of things, you can almost always find an A&P or an FBO. Most airports that a regional airline would fly to, and many that receive NO scheduled airline service, have at least one FBO. Take Martin State Airport (KMTN), a Class D general aviation/reliever airport. The runway's about 7,000 feet long, so it receives quite a bit of bizjet traffic and general aviation. There are 232 aircraft based there, so there's definitely maintenance, between the FBO and the A-10 squadron based on the field. Don't expect to land your J3 Cub and get maintenance from the A-10 guys, but they count as maintenance on-site. According to AirNav, you'll find minor airframe and powerplant service, but no oxygen of any kind. It's a rare airport that has absolutely NO maintenance personnel on-site, even if they're private A&Ps not working for the airport, but I'm sure they exist. Small bush strips (debatable whether or not you can truly call that an airport) might not- the one that comes to mind is Trent Palmer's runway outside his house- he's not an A&P, so no MX on-site. However, it's certainly more common that there's maintenance on the field than not.
Airports usually do not hire maintenance staff for other than maintaining the airport facilities. Companies (Airlines, FBOs) that operate there will usually have a base and have the required staff on site. If you land at an airfield where there is an established FBO and you ding your plane, you could ask them to repair it, if it falls within their operating certification. Otherwise you will have to solicit the services of an organisation based elsewhere.
