The Moon Machines documentary series states the rocket used to get off the moon could never be test fired to make sure that particular rocket engine worked due

The Moon Machines documentary series states the rocket used to get off the moon could never be test fired to make sure that particular rocket engine worked due to the propellant used - the engine had to be rebuilt after each firing, so it was one use only for space vehicles. They compensated for this by using the simplest design possible with self igniting propellant (separate fuel and oxidizer sources).