Learjet 31
Flight Crew Instrument; Flight Crew Multiengine; Flight Crew Commercial
Flight Crew Last 90 Days 12; Flight Crew Total 2585; Flight Crew Type 1658
Aircraft Equipment Problem Critical; Deviation / Discrepancy - Procedural Maintenance
Flight Crew FLC complied w / Automation / Advisory; Flight Crew Returned To Departure Airport; Flight Crew Took Evasive Action; General Maintenance Action; General Declared Emergency
Procedure; Aircraft
I was flying as First Officer on a Learjet 31. We departed for a 1.5 hour flight. This was to be the airplane's first flight following a twelve year inspection. The airplane was test flown by a factory Learjet test pilot previously and declared airworthy; and returned to the maintenance facility. As we climbed through FL360 on our way to FL430; we experienced an abrupt loss of cabin pressure. It sounded as though the Aft Pressure Bulkhead gave way and the cabin VSI immediately pegged at over 6;000 FPM cabin altitude. I informed ATC of the situation and told them we needed an immediate descend. We then donned 02 masks and initiated emergency descend procedures in accordance to the Learjet Aircraft Flight Manual. My priority at that time was to get the airplane as quickly and safely as possible to a safe altitude. As we passed through about 25;000 FT I noticed the emergency pressurization system seemed to have stabilized the cabin climb and I switched back to my regular headset as I was having trouble with my microphone in the O2 mask. I contacted ATC and was given instructions to continue my descent to 12;000 FT. I was asked if I needed to declare an emergency; and I told the Controller the situation seemed to be under control at that point and requested to return to the departure airport. We landed with no further incident and left the airplane at the overhaul facility for repairs.
The Reporter stated that a pressurization duct glue had not completely cured after the extensive overhaul which allowed a duct connection to fail. The aircraft was returned to the overhaul facility where all ducts were inspected and re-glued as necessary.
A Learjet 31 pressurization duct connection failed while climbing through FL360 because the glue connecting a pressurization duct had not completely cured following an extensive maintenance overhaul.