Flight Crew Multiengine; Flight Crew Instrument; Flight Crew Flight Instructor; Flight Crew Air Transport Pilot (ATP)
Flight Crew Last 90 Days 160; Flight Crew Total 5920; Flight Crew Type 1640
Aircraft Equipment Problem Critical
Flight Crew Returned To Departure Airport; General Maintenance Action
Environment - Non Weather Related; Aircraft; Manuals
The Captain worked on the flight plan and fuel order while I got the inside of the aircraft ready and took care of the pre-flight checks. I read through the aircraft logbook to make sure there were no open write ups. The baggage door annunciator had been written up the previous night. The baggage door had been worked on and signed off as ops check good.Upon closing the baggage door after connecting the battery I noticed the annunciation was extinguished. The pre-flight checks were completed and the baggage door was opened to place crew bags inside. Upon closing the baggage door I entered the cockpit to check the baggage door annunciator. It was now illuminated. The Captain and I opened the baggage door and found the forward micro switch pin was stuck in the depressed position. The Captain then called Maintenance Control to have the Mechanic return to the aircraft to check this out.The pin and switch were cleaned and when the baggage door was closed the annunciator extinguished. I then opened and closed the door a few times to make sure the annunciator remained extinguished when the door was closed.  We then proceeded with our trip. About 20 minutes into the flight the baggage door [light] came on intermittently. The Captain flew the plane and worked the radios while I read the checklist. The Captain then transferred the radios and the controls to me and made a phone call to Maintenance Control. We were asked to return to our departure airport by Maintenance Control. I contacted Center and made this request. The airplane controls were then transferred back to the Captain and I continued my duties as pilot not flying.We decided it was best to keep the left engine running due to the previous history of the baggage door annunciator intermittently turning on and off. No emergency was declared. The other purpose for keeping the left engine running was due to a high terrain environment; high altitude airport; high temperature; and the possibility of needing full power on a go around should the need arise. The speed of the aircraft was reduced and the altitude was reduced when cleared to do so. A normal landing was made in APA.
Preflight revealed an ongoing previous days issue with regard to the Baggage Door Red Annunciator. Maintenance was called and arrived to clear the discrepancy. Previous days operation had indicated that the switch wasn't making full contact with the pin of the forward door switch. This was observed on the ground only. Departure 17L to FL320 was normal. In cruise; the Red Bag Door Light illuminated prompting a return per Aircraft Checklist. Checklist was consulted. After brief deliberation; the second in command and I elected to forego the engine securing checklist due to many appropriate concerns regarding but not limited to: pilot in command emergency authority; return airport density altitude; return airport landing runway; traffic; abnormality's validity and authenticity; age of the aircraft; previous multiple days' experience with the issue; previous experience with the same issue on other company aircraft; previous knowledge of bag door departure; safety of crew; previous experience with similar issued related to sensors on the Piaggio; 4500 hours in type. Observed the fix in its entirety on multiple occasions. Being a responsible crew and looking past the obvious on how it might have adversely affected the outcome. Return was normal to find the abnormality was indeed a faulty switch making improper contact. Maintenance performed a complete bag door re-alignment in accordance with the Piaggio Maintenance Manual. This re-alignment cleared the issue. Piaggio Aero has made available a new kit that upgrades the door sensor system that should minimize this occurrence. Either due to unavailability or unwillingness to retrofit older aircraft; the new kit was not installed. It is my belief that an improper maintenance procedure was used to fix the switch initially due to its intermittent nature. During the third attempt in maintenance; the entire procedure was followed which ultimately cleared the discrepancy. An emergency was not declared. No pilot deviation occurred.
Despite repeated maintenance attention to the cargo door warning micro switch prior to departure; the P-180 Flight Crew received a cargo door warning light 20 minutes after takeoff from a high altitude airport.  After consultation with Maintenance they returned to their departure airport; opting to not comply with the checklist requirement that the aft mounted left engine be shut down due to its propiquity to the door.