Pagnotta Engineering

Authority to certify structural modifications and alterations to aircraft

Michael J. Pagnotta has been a Structures DER (Part 23, 25, and 27) since 1996. Modifications or alterations that comply with the
applicable Federal Aviation Regulation (FAR) can be approved by a DER without FAA approval. The DER serves as the "eyes and ears"
of the FAA and approves the modifications or alterations based on the findings of compliance. Demonstrating compliance with the
FAR does not necessarily require structural design or analysis. Testing can be performed to find compliance.

BAC 1-11 Fuselage Modification

Northrop Grumman, Baltimore, MD

• Structural evaluation of fuselage vent holes for heat exchanger and supporting structure
• Created Finite Element Model (FEM) of fuselage section
• Performed stress analysis to ensure compliance with the FAR Part 25
• DER inspection and approval of modifications

Detailed FEM of left side of aft fuselage with
vent holes and doublers
BAC 1-11 fuselage stress contour plot for unit
in-plane loading
BAC 1-11 with modification installed.
(NOTE Staggered holes versus in-line holes
in FEM. Model is conservative.)

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