Flat nose oleo, the shop repaired it. Flew it back to the home airport and left on a 2 week business trip, when I returned it was flat again. The shop repaired it a second time and it held, same repair, except this time the A&P replaced the top o-ring as well. The repair worked. The shop wants to charge me for another repair, and I will deal with that. But I can't help but wonder what would have happened if the oleo collapsed on landing and I would be looking at a prop strike & engine teardown. What if any are the re-test requirements for this? They fixed it and I flew it home, it was a slow leak. Is there any waiting time required to make sure it holds?