Oh No! I Forgot To Put The Gear Down

If you haven't yet had a "gear up" you are lucky, or maybe just well trained and careful. Although I have never had a gear up landing, I almost did.  Years back when I was doing some instrument flight training with an instructor in the right seat, I was on short final ready to touch down. The instructor said "have you forgotten something?"  I had not put the gear down.  That was a close call, but my only one, with over 4,000 hours of flying.  I offer a word of advice.  I have a routine which insures that the landing gear is down properly.  I look for the three green lights and think or say "three in the green."   In 2013 NASA reported an average of 60 gear up landings annually and in 2003 there were 96 reported by the NTSB. In addition, I don't know how many landing gear failures (LGF) occurred which may or may not be included under "gear up".

I just read an incidental study that landing gear ranks second after engines as systems prone to failure.
This is really a separate issue than routine gear ups. That is because the pilot at least tried to raise or lower the gear, but a mechanical situation prevented it from happening. Just to give you an idea of the more common causes of (LGF), I'll relate some given by DVI Aviation*.
          Improper rigging
          Improper repair or maintenance
          Improper installation of parts
          Parts worn beyond allowable service limits
          Failure or fatigue of parts
          Lack of lubrication and or hydraulic fluid
          Etc.

Finally, from a study by Canadian Aircraft Maintenance Management Information Systems**,
largely dealing with military planes, the following was found.  In surveying over 200 landing
gear structural component failures, the main mechanical problems involved: fatigue and corrosion.

So, in summary. Get your landing gear and related systems checked regularly, at least once a year.
During your landing approach, VFR or IFR say "three in the green" at least two or three times, after the gear has been deployed.  Happy, safe landings!

* DVI Aviation-Aviation Safety Experts
**Failure Analysis of Aircraft Landing Gear Components 1992