Narrative:

I started the APU to put the aircraft on its on power. The APU generator would not go on line. Later it was discovered that there were 0 volts and 0 freqs. Maintenance control was discussing the idea of putting the generator on MEL. I called [operations] and explained my feelings of no APU generator and crossing the ocean. I feel very strongly that to leave a maintenance base with a MEL and no back-up generator makes no sense. I requested that the problem either be fixed or we swap with another aircraft. To my surprise and delight another aircraft was the solution to the problem.

Google
 

Original NASA ASRS Text

Title: A B757-200 Captain reported he discovered an dead APU generator before an overwater departure and asked for a replacement aircraft; which was provided.

Narrative: I started the APU to put the aircraft on its on power. The APU generator would not go on line. Later it was discovered that there were 0 volts and 0 freqs. Maintenance Control was discussing the idea of putting the generator on MEL. I called [Operations] and explained my feelings of no APU generator and crossing the ocean. I feel very strongly that to leave a maintenance base with a MEL and no back-up generator makes no sense. I requested that the problem either be fixed or we swap with another aircraft. To my surprise and delight another aircraft was the solution to the problem.

Data retrieved from NASA's ASRS site as of April 2012 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.