DISTRIBUTION A. Approved for public release; distribution unlimited.
EZ-SB-13-003, Page 1 of 5
Number: EZ-SB-13-003
Date: 9 April, 2013
Subject: Revised Initial Flaw Size Assumptions for Slow Crack Growth (SCG)
Metallic Structures
References:
1. Department of Defense Joint Service Specification Guide, Aircraft Structures,
JSSG-2006, 30 October 1998.
2. Department of Defense Standard Practice, Aircraft Structural Integrity Program,
MIL-STD-1530C, 1 November 2005.
3. Structures Bulletin, EN-SB-12-003, Damage Tolerance Inspection Methodology for
Slow Crack Growth Metallic Structure, 23 July 2012.
4. Department of Defense Handbook, Nondestructive Evaluation System Reliability
Assessment, MIL-HDBK-1823A, 7 April 2009.
5. W.D. Rummel, Recommended Practice for Demonstration of Nondestructive
Evaluation (NDE) Reliability on Aircraft Production Parts, Materials Evaluation, Vol.
40, No.9, pp.922-932, American Society for Nondestructive Testing (ASNT), Inc.,
1982.
Background:
The basic concept of slow crack growth damage tolerance approach is that damage is
assumed to exist in each safety-of-flight element of the aircraft structure in the most
critical location and orientation with respect to the stress field. The structure must
successfully sustain the growth of the assumed damage for a specified period of
service, and must maintain a minimum level of residual strength both during and at the
end of this period. USAF damage tolerance design guidelines are specified in
References 1, 2, and 3 and apply to all safety-of-flight structure, i.e., structure whose
failure could cause direct loss of the aircraft, or whose failure, if it remained undetected,
could result in the loss of aircraft or aircrew or cause inadvertent store release.
Structures Bulletin
AFLCMC/EZ
Bldg 28, 2145 Monahan Way
WPAFB, OH 45433-7101
Phone 937-656-9956
