Albatros (L39)
Flight Crew Air Transport Pilot (ATP); Flight Crew Multiengine
Flight Crew Last 90 Days 50; Flight Crew Total 13000; Flight Crew Type 20
Training / Qualification
Aircraft Equipment Problem Critical
Flight Crew Requested ATC Assistance / Clarification; Flight Crew Returned To Departure Airport; General Declared Emergency
Aircraft; Human Factors
I was performing the first leg of a ferry of an L-39 aircraft. The preflight and strap in was performed individually by both myself and my back-seater; a company Mechanic; while the aircraft was still in the hangar. I had us close both canopies in the hangar shade to ensure we had the cockpit to cockpit volume set correctly before we were pulled out to the ramp for a dry start to ensure proper oil service. The oil service level was verified by FBO personnel and after being given the thumbs up; I continued the start with the APU still running. Subsequent after start checks and engine run ups were uneventful. Takeoff and initial climb seemed normal; but in retrospect the noise level in the aircraft was probably higher that normal. I attributed the increase noise level due to not wearing my earplugs as is my normal habit pattern. Climbing through 10;000 FT I observed a cabin altitude warning and notified the Mechanic. I checked the canopy handle; the canopy unlock light; the bleed switch; the ECS and cabin pressure switch; and they were all normal. I reset the cabin pressure lever which depressurized the canopy seal. The canopy immediately rose about 4 inches on the left side and was still attached on the right side. I asked the Mechanic to take the aircraft and I pulled down on the canopy with both hands. It came down about 2 inches and then separated from the aircraft. I took back control of the aircraft; started a descent and turn back to the departure airport and declared an emergency. I asked ATC to mark my position so that I would know the approximate position of the canopy. The engine and aircraft were running fine and I made an uneventful landing. The aircraft was secured and impounded pending an investigation. I received the coordinates and time of the incident after landing. I believe the cause of this incident was due to improper locking of the canopy. Although the canopy lock handle was locked and canopy unlock light was out; the canopy was not locked properly. The company is currently doing an investigation.
The Reporter stated that every L-39 canopy is individually manufactured for a specific aircraft but no two fit the same. This is not the first time a canopy has come off because it was not fully locked. The issue is that the canopy locked indication is activated by the canopy handle. So the light goes out when the handle is in the closed position but it may not in fact by fully closed. Additionally; a pilot cannot see the canopy edges with both the helmet and mask on. The Ukrainian Air Force has someone standby all the way through engine start to observe the canopy because of their experience with this type event. The Reporter's company is now painting white stripes on both the canopy and the aircraft as alignment stripes so that when it is in fact fully closed the stripes will align.
A L-39 Canopy departed in flight climbing though 11;000 FT with air conditioning and indicating systems operating normally.