UCLA Extension

Airframe Design and Repairs

Since most current airframe structures are constructed from aluminum materials, this course focuses primarily on metallic structural design and repairs. It is intended for design, stress, and liaison engineers, and presents the concept of airframe design and repairs, including policy, design considerations, and data not ordinarily covered by standard texts or handbooks. The background of airframe structural design and post-design also is provided, including salvage, retrofit, repairs, modification, structural life extension, maintenance, etc., while emphasizing practical and hands-on experience of metallic airframe structures.

Structural repair methods are introduced for those who need to support aircraft maintenance and repairs and/or modification to meet aircraft safety and structural integrity standards. Lectures emphasize that each repair must be treated as a unique problem and not simply by “universal” methods. Homework assignments are given every day in class.

This course does not require knowledge or background of strength of materials or structural analysis.

Course Materials

The text, Airframe Structural Design, Michael C.Y. Niu (Conmilit Press, 2011), and lecture notes are distributed on the first day of the course. The notes are for participants only and are not for sale.

Coordinator and Lecturer

Michael C.Y. Niu, MS, President, AD Airframe Consulting Company, Granada Hills, California. Mr. Niu is a metallic and composite airframe consultant who has acquired over 35 years’ experience in aerospace and airframe structural analysis and design, and was a senior research and development engineer (management position) at Lockheed Aeronautical Systems Company. As department manager in charge of various structural programs there, he was responsible for the development of innovative metallic and composite structural design concepts applicable to current and future advanced tactical fighters and advanced transports. He also was involved in conceptual and preliminary airplane design, and was lead stress engineer responsible for the L-1011 wide-body aircraft wing and empennage structures. During 1966 and 1968 he served as stress engineer for the B727, B747, and other aircraft at The Boeing Company in Seattle. Mr. Niu is the author of Airframe Structural Design (1988), Airframe Stress Analysis and Sizing (1999), and Composite Airframe Structures (1992). He also has written Lockheed’s Composites Design Guide and Composites Drafting Handbook. He received the Lockheed Award of Achievement and Award of Product Excellence in 1973 and 1986, respectively. Mr. Niu is listed in Who’s Who in Aviation, 1973.

Daily Schedule

Day 1

General References

Design for safety, low structural weight, and manufacturing (low cost); design criteria and regulations; roles of airframe design; how an aircraft is built.

Structural external and internal loads, static and dynamic load, wing and empennage loads, fuselage loads.

Material Selection
Material properties, material selection, fatigue and crack growth characteristic.

Structural Joints
Types of joint, fastener selection, under ultimate and fatigue loads, shim and eccentricity effects, lugs (pin in shear) and tension fittings (bolt in tension), fatigue considerations.

Day 2

Damage-Tolerant Design
Fatigue design considerations, stress concentration, crack growth and fail-fail characteristics.

Wing and Empennage Design
Integration of wing box, fatigue and fail-safe design, cover panel configurations, selection criteria of wing upper and lower panels, spars and ribs, wing root-joints, empennage design.

Wing Edges
Leading and trailing edges, slats, ailerons, flaps and spoilers, hinge design, stiffness (EI and GJ) effect, forced bending.

Fuselage Design
Integration of fuselage structures, cross-sectional selection, skin-stringer panels, frames and bulkheads, floor beams, doors and windows, intersection of fuselage and wing, fatigue and fail-safe design.

Day 3

Engine and Landing Gear Supports
Pylons and types of construction, landing gear supports, determinate and indeterminate design.

Cutouts and Doors
Cutout requirements, cutouts in wing and empennage boxes, cutouts in fuselage.

Airframe classifications, accessibility, policy and requirements, inspectability, maintainability, repairability, airframe modification and conversion.

Salvage policy and considerations, liaison engineer’s responsibilities, causes of salvage, “use-as-is” salvage, mis-drilled hastener hole with freeze plug.

Non-Standard Joints
Special fasteners and dissimilar fasteners, fastener selection and fastener hole requirements, rows of fastener joints, shim and short edge distance, fastener spacing.

Day 4

Standard repairs and procedures, degradation of structure due to repair, flush vs. non-flush repairs, effect of doubler size and shape, oversize or next-size fasteners.

Post-Design Overview: Wing and Fuselage
Repair and retrofit design cases, wing and empennage skin-stringer panels, fuselage skin-stringer panels, frames and bulkheads, spars and ribs, derivative and modification cases.

Full-Scale Airframe Tests
Importance of full-scale airframe tests, full-scale airframe fatigue test, full-scale airframe static test, and iron bird functional tests.

Inspection and maintenance, corrosion control, Murphy’s law, new design vs. post-design; airframe life extension program.

For more information contact the Short Course Program Office:
shortcourses@uclaextension.edu | (310) 825-3344 | fax (310) 206-2815