The F111C wing pivot fitting repair and its implications for the design/assessment of bonded joints and composite repairs

Lorrie Molent, Rhys Jones

Research output: Chapter in Book/Report/Conference proceedingChapter (Book)Researchpeer-review

3 Citations (Scopus)


This chapter discusses the development of a bonded composite reinforcement to the integrally stiffened D6ac steel wing pivot fitting (WPF) of F-111 aircraft while in-service with the Royal Australian Air Force (RAAF). Particular attention is given to the building block approach and as such describes the finite element and experimental program used to determine improved stiffener runout geometry as well as the full-scale wing tests required to validate the computed stress reduction. Other aspects of this reinforcement are discussed in this chapter. This represents the first bonded reinforcement to primary structure and was successful in that by reducing the strains at the critical location by approximately 30% it achieved its primary objective namely to stop cracking and wing failure in the RAAF F-111 fleet and Cold Proof Load Test (CPLT; explained later). A significant outcome of the F-111 WPF reinforcement program was that it resulted in a detailed understanding of the design/assessment tools needed for designing damage tolerant repairs to meet the stringent damage tolerant requirements inherent in both JSSG2006 and FAA ac-120-107b. It is also shown that the in-service performance of the WPF reinforcement reveals shortcomings in the approach outlined in the US Composite Materials Handbook CMH-17-3G for the design of bonded joints. It is also shown that not only was the WPF reinforcement the first example of the ability of composite repair technology to eliminate cracking in primary structure it was also the first example to highlight the benefit to be gained by combining composite repair technology with shape optimisation or rework.

Original languageEnglish
Title of host publicationAircraft Sustainment and Repair
EditorsRhys Jones, Alan Baker, Neil Matthews, Victor Champagne
Place of PublicationOxford UK
Number of pages33
ISBN (Electronic)9780081005446
ISBN (Print)9780081005408
Publication statusPublished - 2018


  • Design optimisation
  • Full-scale testing
  • Infrared thermography
  • Optimisation
  • Pabst
  • Primary structure

Cite this

Molent, L., & Jones, R. (2018). The F111C wing pivot fitting repair and its implications for the design/assessment of bonded joints and composite repairs. In R. Jones, A. Baker, N. Matthews, & V. Champagne (Eds.), Aircraft Sustainment and Repair (1st ed., pp. 511-543). Elsevier.