Service difficulty report · Interlock · Schler ASK21

Difficulty date
March 21, 2011
Submitted
March 21, 2011
Operation
General aviation
Aircraft
N955TS
Make and model
Schler ASK21
Aircraft serial
21815
Aircraft time
800 hours, 2,000 cycles
Part
Interlock
Part number
AS21CAN120
Condition
Grooved
Location
Canopy
Part time
800 hours, 2,000 cycles
Stage of operation
TO
How discovered
C
Nature of condition
D
Precautionary procedure
C

As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.

What was found

CANOPY INTERLOCKS ARE FABRICATED FROM A NYLON OR DELRON SYNTHETIC MATERIAL THAT BECAME WORN IN AN UNSEEN LOCATION. THE WEAR IS FROM THE FORWARD CANOPY METAL LOCKING ROD CONTINUOUSLY PUSHING OVER THE PLASTIC INTERLOCK. THE WORN INTERLOCK EVENTUALLY DID NOT ALLOW THE REAR CANOPY LOCKING ROD TO ENGAGE INTO IT'S LOCKED POSITION. DURING TAKEOFF, THE AERODYNAMIC FORCES PULLED THE CANOPY OPEN AND BLEW OUT THE PLEXIGLASS AND BENT THE CANOPY SUPPORT STRUCTURE. CHECKED OTHER TWO AIRCRAFT OF SAME TYPE AND BOTH SHOWED THE SAME WEAR AND DEFECT. SUGGEST INTERLOCK PART BE MADE FROM A MORE RESILIENT MATERIAL.