MD-80 Series (DC-9-80) Undifferentiated or Other Model
Flight Crew Air Transport Pilot (ATP)
Communication Breakdown; Confusion; Situational Awareness
Aircraft Equipment Problem Less Severe; Deviation / Discrepancy - Procedural FAR; Deviation / Discrepancy - Procedural Published Material / Policy; Deviation / Discrepancy - Procedural Maintenance
General Maintenance Action
Aircraft; Human Factors; Procedure
During my preflight I noticed that the longitudinal trim pointer tip was missing.The longitudinal and aileron trim pointer tips on the MD-80 are tritium-gas filled capsules. Tritium is a radioactive gas that emits electrons while it decays. Those electrons then excite the gas-filled capsule so that it glows as a self-powered gas even in the absence of any direct light source. It is designed that way so that the pilots would be able to trim the airplane in the event of a complete power failure in darkness.Well;the longitudinal trim pointer was missing and maintenance signed off the logbook saying that according to McDonnell Douglas Service Bulletin the pointer tip was not required anymore. I accepted the airplane; however; having gotten bogus sign-off's before I promised myself to obtain that bulletin and see for myself. I did and unfortunately; that service bulletin deals with modifications to the internal jack-screw mechanism. There is not one word in the whole bulletin that would give anyone rise to believe that the pointer tips can be missing.I checked the maintenance manual. It actually says that if the pointers are damaged or broken than everybody would have to leave the cockpit as tritium gas is radioactive/toxic and hazmat procedures have to be followed. How do I know that the missing tip is not somewhere lying broken inside the center pedestal? The bulletin gives no relief to fly with missing pointer tips. Why did maintenance sign off the logbook with a reference that does not address the discrepancy? How are pilots supposed to safeguard against bogus sign-off's if we do not have access to the documentation that is being referenced? The pointer tips are not mentioned in our MEL book? Can I now assume that either they are installed or if missing the airplane is not airworthy?
The pilot of a MD-80 questioned the practice of signing off missing trim pointers that appear to contain toxic material.