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Aerospace – Canopy Leakage

Reasons why an aircraft canopy leaks

Fishbon template on canopy leakage

The transparent enclosure that provides a controlled or pressurized environment for small aircraft occupants is a canopy. The enclosure allows a broad field view compared to a traditional flight deck. A canopy’s shape is designed in a unique way to minimize aerodynamic drag. Its unique formation is to gain maximum visibility for pilots and other crewmembers. The canopy may get detached due to leakage if not maintained properly or due to improper design. This visual analysis contains the potential reasons for a canopy leakage with the help of a fishbone diagram.

Canopy Leakage


  •  From the assembly process-Non observed but have identified the order of assembly operation changes to       further protect from FOD induction
  •  From aircraft-Confirmed
  •  Shipping and handling-Unit are capped at the Final out


  •  AC system leakage would pass ATP upon return
  •  Over pressurization, damaging components-Valve has a pressure relief


  •  Poppet out of round and surface finish
  •  Check valve seat out of round and surface finish
  •  Seat oversized-Poppet is cone shape-Contained
  •  Poppet alignment at the assembly level
  •  Anodize or paint the seat surface

 Component Failure

  •  Supplier regulator malfunction-Regulator not in action during the leakage test
  •  Solenoid failure
  •  Solenoid voltage residual dropout
  •  Solenoid not fully closing
  •  Valve body leakage-Test confirmed no body leakage
  •  Relief valve seat leakage


  •  Material analysis of poppet and seat assembly
  •  Check valve bore material and galling
  •  Spring force/ rates-Not in action for reverse flow check
  •  Spring rate variation-Not in action for reverse flow


  •  Standard reseating practices-Removed seating tools to prevent the practice. Contained


  •  Test bench calibration
  •   Bench test setup/ ATP-Check for leakage of the system at the bench


  •  Design allows leakage
  •  Variation in poppet seat design allows for different decay rates
  •  Tolerance build-up
  •  Check valve design allows FOD to settle at the check valve


  •  FOD induced during assembly
  •  Improper assembly of poppets

To understand the reasons for canopy failure easily, the root cause analysis of the vital causes in a structured fishbone template is necessary. We have listed below how and why this template is advantageous so that one can think of some preventive measures to avoid disaster and fatal accidents.

Who should use the Canopy Leakage template?

  • Anyone who wants to understand why an aircraft canopy leaks.

Why use this template?

  • Brisk understanding of the causes of a leak in aircraft canopy.
  • Tailor this template using smartQED for your problem-solving.
  • Design your templates for different types of problems and incident analysis in smartQED.

Curated from community experience and public sources:

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