(2)
For redundant structure, in which the failure of individual elements would resultin appliedloadsbeing safelydistributedto otherload carrying members, 90 percent probability with 95 percent con.dence.]

(c)
The e.ects of temperature on allowable stresses used for design in an essential com-ponent or structure must be considered where thermal e.ects are signi.cant under normal operating conditions.

(d)
The strength,detaildesign,andfabricationof the structuremust minimizethepro-bability of disastrous fatigue failure, particularly at points of stress concentration.

(e)
[Greaterdesignvaluesmaybeusedifa ”premiumselection” of thematerialismade in which a specimen of each individual item is tested before use to determine that the actual strength properties of that particular item will equal or exceed those used in design.]

Amdt. 25-72, E.. 8/20/90
′
Elodie Roux. Septembre 2003
Subpart D : Design and Construction
FAR25.615 :[Removed.]
[Removed.] Amdt. 25-72, E.. 8/20/90
FAR 25.619 : Special factors.
[The factor of safety prescribed in Sec. 25.303 must be multiplied by the highest pertinent specialfactor of safetyprescribedinSecs.25.621 through25.625for eachpart of the structure whose strength is–]
(a)
Uncertain;

(b)
Likely to deteriorate in service before normal replacement; or

(c)
Subjectto appreciable variabilitybecause ofuncertaintiesin manufacturingprocesses

or inspection methods. Amdt. 25-23, E.. 5/8/70
FAR 25.621 : Casting factors.
(a)
General.Thefactors,tests, andinspections speci.edinparagraphs(b) through(d) of this section must be applied in addition to those necessary to establish foundry qualitycontrol.The inspections must meet approved speci.cations.Paragraphs(c) and (d) of this section apply to any structural castings except castings that are pressure tested as parts of hydraulic or other .uid systems and do not support structural loads.

(b)
Bearing stresses and surfaces.The castingfactorsspeci.edinparagraphs(c) and (d)of this section–

(1)
Need not exceed1.25 with respect to bearing stresses regardless of the method of inspection used; and

(2)
Need notbe used with respecttothebearing surfaces of apart whosebearing factor is larger than the applicable casting factor.

(c)
Critical castings.Foreach casting whosefailurewouldprecludecontinued safe .ight and landing of the airplane or result in serious injury to occupants, the following apply :

(1)
Each critical casting must–

(i)
Have a casting factor of not less than 1.25; and

(ii)
Receive100percentinspectionbyvisual, radiographic, and magneticpar-ticleorpenetrantinspection methods orapproved equivalentnondestruc-tive inspection methods.

(2)
For each critical casting with a casting factor less than 1.50, three sample castings must be static tested and shown to meet–

(i)
The strength requirements of Sec. 25.305 at an ultimate load correspon-ding to a casting factor of 1.25; and

(ii)
The deformation requirements of Sec. 25.305 at a load of 1.15 times the limit load.

(3)
Examples of these castings are structural attachment .ttings, parts of .ight control systems, control surface hinges and balance weight attachments, seat, berth, safety belt, and fuel and oil tank supports and attachments, and cabin pressure valves.

(d) Noncritical castings.For each casting otherthanthose speci.edinparagraph(c) of this section, the following apply :
(1)
Except asprovidedin subparagraphs(2) and(3) of thisparagraph, the casting factors and corresponding inspections must meet the following table :

(2)
The percentage of castings inspected by nonvisual methods may be reduced belowthat speci.edin subparagraph(1) of thisparagraph when an approved quality control procedure is established.
　
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