U.S. Department 

Advisory

of Transportation 

Federal Aviation 

Administration

Circular 

Subject: MATERIAL STRENGTH 

PROPERTIES AND MATERIAL 

DESIGN VALUES 

Date: 8/6/03 

Initiated by: ANM-115

AC No: 25.613-1 

Change: 

1. PURPOSE. This advisory circular (AC) provides guidance for demonstrating compliance 

with the airworthiness standards that specify the requirements for material strength properties and 

material design values. This guidance is applicable to transport category airplanes for which a 

new, amended, or supplemental type certificate is requested. 

2. APPLICABILITY. 

a. The guidance provided in this document is directed to airplane manufacturers, modifiers, 

foreign regulatory authorities, and Federal Aviation Administration transport airplane type 

certification engineers and their designees. 

b. This material is neither mandatory nor regulatory in nature and does not constitute a 

regulation. It describes acceptable means, but not the only means, for demonstrating compliance 

with the applicable regulations. The Federal Aviation Administration will consider other methods 

of demonstrating compliance that an applicant may elect to present. While these guidelines are not 

mandatory, they are derived from extensive FAA and industry experience in determining 

compliance with the relevant regulations. On the other hand, if we become aware of 

circumstances that convince us that following this AC would not result in compliance with the 

applicable regulations, we will not be bound by the terms of this AC, and we may require 

additional substantiation or design changes as a basis for finding compliance. 

c. This material does not change, create any additional, authorize changes in, or permit 

deviations from, regulatory requirements. 

3. RELATED FAR SECTIONS. Section 25.613 of 14 CFR part 25. 

4. RELATED ADVISORY CIRCULARS. 

• Advisory Circular (AC) 25.571-1C, Damage-Tolerance and Fatigue Evaluation of 

Structure; and 

• AC 20-107A, Composite Aircraft Structure. 
AC 25.613-1 8/6/03 

5. DEFINITIONS. 

 a. Material Strength Properties. Material properties that define the strength related 

characteristics of any given material. Typical examples of material strength properties are ultimate 

and yield values for compression, tension, bearing, shear, etc. 

 b. Material Design Values. Material strength properties that have been established based on 

the requirements of § 25.613 (b), or by other means as defined in this AC. These values are 

generally statistically determined based on enough data that, when used for design, the probability 

of structural failure due to material variability will be minimized. Typical values for moduli are 

used. 

 c. Airplane Operating Envelope. The operating limitations defined by the applicant under 

subpart G of part 25. 

6. BACKGROUND. Metallic material strength properties and design values for airplanes 

manufactured in the U.S. have traditionally been based on those contained in Military Handbook 

(MIL-HDBK)-5. For materials not listed in that handbook, the statistical procedures in the 

handbook were normally used by U.S. manufacturers to determine design values. European 

manufacturers additionally used design values and methods specified in ESDU 00932, Metallic 

Data Handbook, or other equivalent approved material data. Until Amendment 25-72 to part 25 of 

the FAR, the "A" or "B" material design values listed in MIL-HDBK-5, or those listed in MILHDBK-17, -23, or Army-Navy-Commerce (ANC) -18, were required to be used, unless specific 

FAA approval was granted for other approaches. Sections 25.613 and 25.615 were amended in 

1992, combining them into one requirement, § 25.613, and deleting the reference to MIL-HDBK5. As part of the revision, the requirement to use A and B allowables of the military handbook 

was replaced by a requirement to attain certain levels of probability and confidence for strength, 

with the statistical method unspecified. Those probability and confidence levels apply to metallic 

as well as non-metallic materials. AC 20-107A contains information regarding compliance with 

§ 25.613 for composite materials, and the use of MIL-HDBK-17. 

On January 31, 2003 the Metallic Materials Properties Development and Standardization 

(MMPDS) Handbook was first published as the replacement document for MIL-HDBK-5. On that 

date both MMPDS-01 and MIL-HDBK-5J were published, and are technically equivalent. 

Henceforth, changes to the technical data in these documents will be promulgated as revisions to 

the MMPDS Handbook, under the cognizance of the FAA, and there will be no further revisions to 

MIL-HDBK-5. In using this Advisory Circular, MMPDS data may be accepted in lieu of MILHDBK-5 data, as they are considered to be technically equivalent. 

7. DISCUSSION. 

 a. Statistically Based Design Values. Design values required by § 25.613 should be based 

on sufficient testing to assure a high degree of confidence in the values. In all cases, a statistical 

analysis of the test data should be performed. 

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8/6/03 AC 25.613-1 

(1) The A and B properties published in MIL-HDBK-5 or ESDU 00932 are acceptable, 

as are the statistical methods specified in the applicable chapters/sections of those handbooks. 

Other methods of developing material design values may be acceptable to the FAA. 

(2) The test specimens used for material property certification testing should be made 

from material produced using production processes. Test specimen design, test methods, and 

testing should: 

(a) Conform to universally accepted standards such as those of the American 

Society for Testing Materials (ASTM), European Aerospace Series Standards (EN), International 

Standard Organization (ISO), or other national standards acceptable to the FAA; or 

(b) Conform to those detailed in the applicable chapters/sections of MIL-HDBK-5, 

MIL-HDBK-17, ESDU 00932, or other accepted equivalent material data handbooks; or 

(c) Be accomplished in accordance with an approved test plan which includes 

definition of test specimens and test methods. This provision would be used, for example, when 

the material design values are to be based on tests that include effects of specific geometry and 

design features as well as material. 

(3) The FAA may approve the use of other material test data after review of test 

specimen design, test methods, and test procedures that were used to generate the data. 

 b. Consideration of Environmental Conditions. The material strength properties of a number 

of materials, such as non-metallic composites and adhesives, can be significantly affected by 

temperature as well as moisture absorption. For these materials, the effects of temperature and 

moisture should be accounted for in the determination and use of material design values. This 

determination should include the extremes of the conditions encountered within the airplane 

operating envelope. For example, the maximum temperature of a control surface may include 

effects of direct and reflected solar radiation, convection and radiation from a black runway 

surface, and the maximum ambient temperature. Environmental conditions other than those 

mentioned may also have significant effects on material design values for some materials and 

should be considered. 

 c. Use of Higher Design Values Based on Premium Selection. Design values greater than 

those determined under § 25.613(b) may be used if a premium selection process is employed in 

accordance with § 25.613(e). In that process, individual specimens are tested to determine the 

actual strength properties of each part to be installed on the aircraft, to assure that the strength will 

not be less than that used for design. 

(1) If the material is known to be anisotropic, then testing should account for this 

condition. 

(2) If premium selection is to be used, the test procedures and acceptance criteria should 

be specified on the design drawing. 

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AC 25.613-1 8/6/03 

 d. Other Material Design Values. Previously used material design values, with 

consideration of the source, service experience, and application, may be approved by the 

Administrator on a case-by-case basis (e.g., "S" values of MIL-HDBK-5 or ESDU 00932). 

 e. Material Specifications and Processes. Materials should be produced using production 

specifications and processes accepted by the FAA. 

/s/ Vi L. Lipski 

Manager, Transport Airplane Directorate 

Aircraft Certification Service 

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