Most applicants are familiar with the items listed in §91.205 (remember “TOMATOFLAMES” anybody?).  As pilots we are taught early on that the equipment listed in §91.205 must be operational.  But what happens if something not listed in §91.205 is inoperative?  A dated but still valid guiding document for this dilemma is AC 91.67.  This AC discusses the use of a Minimum Equipment List (MEL).  A MEL solves this problem by providing guidance as to what must be done (or what you can do) if some component not listed in §91.205 is inoperative.  But what to do if your airplane doesn’t have a MEL?  Check out chapter 2 of AC 91.67.  Chapter 2 provides a step by step guideline for what the pilot must do to ensure the airplane is both safe and legal to fly.  The first step is to check the equipment list or “kinds of equipment” list.  Here are some examples of a “kinds of equipment” list:

The example above is from a C172M POH and is not very specific. Note that there is no addtional “equipment list” for this model.

This is from a C172N POH and not much better, also no equipment list.  And below we have a newer model, a C172S.  The C172 lists “kinds of operation” and then goes further with a equipment list.  This helps because the equipment list will state whether or not you can fly with a component inoperative.  Remember, an equipment list IS NOT an MEL.  They sound similar but in this usage they are two completely different animals.

Next, go to step 2 and check the type certificate requirements.  Search for “type certificate data sheet” (TCDS) for your aircraft.  Again you may find that not much information is provided for the older airplanes such as the C172M and C172N.  The newer aircraft may have more information.   The next step is to search for Airworthiness Directives (AD) that might have required the installation of the component that is inoperative.  Finally, if you haven’t found the item in one of the previous steps then go back to §91.205 to see what applies for your flight.    Night time flight?  Then you need the equipment listed in §91.205 (b) and (c).  The AC also says to check other pertinent regulations such as §91.207, §91.215. If after going through the regulations you find that your inopertive component is not listed then you may be able to deactivate/remove it, placard it, and continue to fly.  I say “may” because you might need an A&P to do the work.  As the pilot in command (and a pilot applying for a rating) you should be familiar with the procedures for determining the airworthiness of your airplane both with, and without, a minimum equipment list.