Case Study: Did I need to declare an emergency? I am a fairly newly minted private pilot licensee (PPL). I had just taken off from a small private, (but open to the public) airfield. We are under the shelf of Class B, but are G up to 700 and then E to the B above at 4000.

My instructor noticed our oil Pressure gauge was very close to the red line, and so of course we  headed back. I was about to make a call to inform CTAF we would be crossing midfield and joining the left down wind. Instructor takes control and makes a call asking if any others are in the pattern. Then declare that we will be entering a right down wind (we are a left hand field).

A voice pipes up: Are you declaring an emergency?. I reply no, this is an urgency. (By now the wisdom of my instructor's decision to not cross midfield was clear: It would take much less time to land; it kept us out over paddocks should the situation get worse; It would not take us over houses as the left down wind would.)

Said voice pipes up again: This is the airfield manager, you must declare an emergency if you are using a right hand pattern. My Instructor told me to ignore him and make another call to CTAF asking for any traffic to report position. There was no traffic. We landed without incident.

Who was correct? The manager or us- and does anyone have a FAR/REF to support the conclusion. The old adage Aviate, Navigate, Communicate seems to apply here - but what might the manager be basing his claim on and why?
Before we delve into this one.  Let's be clear that it is much easier for us to sit at a computer with books in hand and review decisions made under urgent circumstances.

Technically, the airport manager was correct here because per 14 CFR §91.126(b)(1):


  "Each pilot of an airplane must make all turns of that airplane to the
  left unless the airport displays approved light signals or visual
  markings indicating that turns should be made to the right..."


There do not appear to be any caveats to that rule.

To un-bind a flight from this rule, one would need to take advantage of §91.3(b)


  "In an in-flight emergency requiring immediate action, the pilot in
  command may deviate from any rule of this part to the extent required
  to meet that emergency."


In my personal experience, I have seen plenty of pilots fly around the pattern in whichever manner is convenient to them; entering on right or left bases for final, approaching for VFR straight-in landings from 15 miles out, etc.  So far, I haven't seen any repercussions for these actions, which is probably why your instructor did not agree with the airport manager.

Another thing that shouldn't go without being said is that this situation was none of the airport manager's darn business.

By verbally acknowledging that there was not an emergency, your instructor placed a liability on himself.  §91.3(b) allows the pilot to deviate from a part 91 rule, but to my knowledge, there is no statute that actually requires recognition of an emergency to be verbally declared or announced under non-ATC-controlled VFR flight.

By leaving the question, "is there an emergency?", unanswered, there is a chance to retrospectively say, "yes, we had an emergency and that's why we deviated from the rule."  However, since he told the airport manager that it was only an urgency he kind of shot himself in the foot if someone were to decide to raise the right turn as a legal issue, but I would be very surprised if anyone does.

To summarize and give you a more direct answer.  


You had a valid emergency
You had no responsibility to verbally declare it
You did deviate from a legal regulation to meet the needs of that emergency 


Sounds to me like you've got a very competent instructor.

Edit: I came across this Letter of Interpretation, which is sort of related to your situation.