I’m going to give you a little bit of maintenance advice from a mechanic who has been dealing with stuff like this for 20 years:
Rule No. 1: Never, ever take the pilot’s words at face value. This is not a sleight against pilots but they just don’t speak the same language as we do. They are not taught to troubleshoot, investigate, or do anything remotely close to helping you fix the airplane. If they say “shear pin” it’s about as valuable as them saying “magical bolt.” I don’t mean that to sound nasty, but if you followed the flight crews’ recommendations on how to fix the problem, the plane would just sit forever. Their training and our training are simply not equal.
Rule 2: You are the Doctor, the pilot and his airplane are the patient. This falls somewhat in line with Rule #1. When a patient comes in and says something is wrong with his leg, that’s about all a doctor gets. That’s the level you should keep it at. Ask any doctor and they’ll almost completely agree that having patients diagnose themselves is NOT a good idea. Are they completely incapable? No. However, their depth of knowledge and access to information is simply nowhere near as great as ours is. Don’t let them steer you into the land of outliers.
Rule #3: Occam’s Razor: The simplest explanation is often the best explanation. That is... maybe a nose landing gear valve is stuck and the crew, knowing nothing about the world of aviation maintenance, declared it as a shear pin. The valve is most likely stuck due to mechanical failure or someone left the LOCKOUT pin installed while performing maintenance. Again, refer to rules 1 and 2.
Rule #4: A flight crew who cries wolf is actually right once in a while. This seems contradictory to rules 1 & 2 but it’s not. You see this sometimes with a flight crew member who consistently is incorrect about something. You see their ID number, remember it, and then think “Oh yeah... This is the guy who should be driving a bus, not an airplane.” As a result, you just sign it off. This is a fundamental flaw, like that of a doctor with a hypochondriac patient... you should always investigate on the basis of greatest caution.
Rule # 5: Don’t let anyone ever push you into a diagnosis or an ETIC. If the plane is down for 25 years and growing roots because of your estimated repair time, then so be it. By all means, do everything you can to get the plane up in a safe manner, but don’t cut corners to make a lead or manager happy. They can go to hell. Just investigate and do what’s necessary.
Rule # 6: If you don’t believe me about Rule #1 and #2, get into a conversation with a pilot about how flight crews enter their flight plan into the FMS. You’ll soon find out that you know nothing about it and they know everything about it. Then show them the system schematic of the FMS system and you’ll see their eyes get a befuddled look at what it all means while you stare confidently ahead. We just don’t speak the same language, PERIOD.