5 asr - airworthiness requirements

7/25/2019 5 ASR - Airworthiness Requirements

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Airworthiness Requirements

Part 5


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REGULATION

Part 5A


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3

THE PERSPECTIVE OF INTERNATIONAL AIR NAVIGATION

CONVENTION &

ARTICLES

ADOPTION OF INTERNATIONAL

STANDARDS AND PROCEDURES (SARPS)

(ANNEXES)

CONCLUDED MANDATING

COMPLIANCE

CONTRACTING STATES

DEVELOP

LAWS

REGULATIONS

REQUIREMENTS

GUIDANCE MATERIALS

CONTRACTING STATES

NATIONAL AVIATION

AUTHORITY (NAA)IMPLEMENTATION

OV

ERSIGHT


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WHAT IS ICAO?

Convention on International Civil Aviation(also known asChicago Convention), was signed on 7 December 1944 by 52States

Pending ratification of the Convention, the ProvisionalInternational Civil Aviation Organization (PICAO) was established

ICAO came into being on 4 April 1947

ICAO became a specialized agency of the United Nations (UN)

linked to Economic and Social Council (ECOSOC)

TO BE THE GLOBAL FORUM FOR CIVIL AVIATION

Currently there are 189 contracting States.

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ICAO ANNEXES

The convention has 18 annexes: Annex 1 - Personnel Licensing Annex 2 - Rules of the Air Annex 3 - Meteorological Service for International Air Navigation Annex 4 - Aeronautical Charts Annex 5 - Units of Measurement to be Used in Air and Ground Operations Annex 6 - Operation of Aircraft - Aeroplanes Annex 7 - Aircraft Nationality and Registration Marks Annex 8 - Airworthiness of Aircraft Annex 9 - Facilitation Annex 10 - Aeronautical Telecommunications Annex 11 - Air Traffic Services Annex 12 - Search and Rescue Annex 13 - Aircraft Accident and Incident Investigation

Annex 14 - Aerodromes - Aerodrome Design and Operations, Heliports Annex 15 - Aeronautical Information Services Annex 16 - Environmental Protection - Aircraft Noise Annex 17 - Security: Safeguarding International Civil Aviation Against Acts of

Unlawful Interference Annex 18 - The Safe Transport of Dangerous Goods by Air Annex 19Safety Management

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AIRWORTHINESS

Part 5B


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ICAO STANDARDS

ICAO standards are developed in the forms of Standards and RecommendedPractices (collectively referred to as SARPs) and Guidance Material.

A Standardis defined as any specification, the uniform application of which isrecognized as necessary for the safety or regularity of international airnavigation and to which Contracting States will conform in accordance withthe Convention

A Recommended Practiceis any specification, the uniform application ofwhich is recognized as desirable in the interest of safety, regularity orefficiency of international air navigation, and to which Contracting States willEndeavour to conform in accordance with the Convention.

SARPs are formulated in broad terms and restricted to essential requirements.

SARPs material is constructed in two sections: core SARPs - material of afundamental regulatory nature contained within the main body of theAnnexes, and detailed technical specifications placed either in Appendices toAnnexes or in Manuals.

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Airworthiness

The aircraftconform to

its TypeCertificate

(TC).

The aircraftis in a

condition forsafe

operation.

airworthy

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If either of the two conditions above cannot be met,

the aircraft is considered to be un-airworthy.


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EASA CERTIFICATION SPECIFICATIONS

CS-22 (Sailplanes and Powered Sailplanes)

CS-23 (Normal, Utility, Aerobatic and Commuter Aeroplanes)

CS-25 (Large Aeroplanes)

CS-27 (Small Rotorcraft)

CS-29 (Large Rotorcraft)

CS-31HB (Hot Air Balloons)

CS-34 (Aircraft Engine Emissions and Fuel Venting)

CS-36 (Aircraft Noise)

CS-APU (Auxiliary Power Units)

CS-AWO (All Weather Operations)

CS-E (Engines) CS-ETSO (European Technical Standard Orders)

CS-P (Propellers)

CS-VLA (Very Light Aeroplanes)

CS-VLR (Very Light Rotorcraft)


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WHAT IS LARGE AEROPLANE?


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CS RELATED TO AIRCRAFT STRUCTURES


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Subpart C - Structure

General

Flight Loads

Flight Manoeuvre and Gust Conditions

Supplementary Conditions Control Surface and System Loads

Ground Loads

Water Loads

Emergency Landing Conditions

Fatigue Evaluation

Lightning protection


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Loads

Sec. 25.301 Loads.

(a) Strength requirements are specified in terms of l imi t lo ads (themaximum loads to be expected in serv ice) and ultimate loads(limit loads multiplied by prescribed factors of safety). Unlessotherwise provided, prescribed loads are limit loads.

(b) Unless otherwise provided, the specified air, ground, and water loadsmust be placed in equilibrium with inertia forces, considering each item ofmass in the airplane. These loads must be distributed to conservativelyapproximate or closely represent actual conditions. Methods used todetermine load intensities and distribution must be validated by flight

load measurement unless the methods used for determining thoseloading conditions are shown to be reliable.

(c) If deflections under load would significantly change the distribution ofexternal or internal loads, this redistribution must be taken into account.


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Factor of safety

Sec. 25.303 Factor of safety.

Unless otherwise specified, a factor of safety of

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must be applied to the prescribed limit load which areconsidered external loads on the structure. When a

loading condition is prescribed in terms of ultimate loads,

a factor of safety need not be applied unless otherwise

specified.


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Subpart D - Design and Construction

General

Control Surfaces

Control Systems

Landing Gear Floats and Hulls

Personnel and Cargo Accommodations

Emergency Provisions

Ventilation and Heating

Pressurization

Fire Protection

Miscellaneous


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Materials

Sec. 25.603 Materials.

The suitability and durability of materials used for parts,the failure of which could adversely affect safety, must

(a) Be established on the basis of experience or tests;

(b) Conform to approved specifications (such as industry ormilitary specifications, or Technical Standard Orders) that ensure

their having the strength and other properties assumed in thedesign data; and

(c) Take into account the effects of environmental conditions,such as temperature and humidity, expected in service.


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Fabrication methods

Sec. 25.605 Fabrication methods.

(a) The methods of fabrication used must

produce a consistently sound structure. If afabrication process (such as gluing, spot welding,or heat treating) requires close control to reachthis objective, the process must be performedunder an approved process specification.

(b) Each new aircraft fabrication method must besubstantiated by a test program.


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Fasteners

Sec. 25.607 Fasteners.

(a) Each removable bolt, screw, nut, pin, or other removable fastener mustincorporate two separate locking devices if

(1) Its loss could preclude continued flight and landing within the designlimitations of the airplane using normal pilot skill and strength; or

(2) Its loss could result in reduction in pitch, yaw, or roll control capability orresponse below that required by Subpart B of this chapter.

(b) The fasteners specified in paragraph (a) of this section and their locking

devices may not be adversely affected by the environmental conditionsassociated with the particular installation.

(c) No self-locking nut may be used on any bolt subject to rotation inoperation unless a non friction locking device is used in addition to theself-locking device.


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Protection of structure

Sec. 25.609 Protection of structure.

Each part of the structure must

(a) Be suitably protected against deterioration or loss ofstrength in service due to any cause, including

(1) Weathering;

(2) Corrosion; and

(3) Abrasion; and

(b) Have provisions for ventilation and drainage wherenecessary for protection.


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Material strength properties and design values

Sec. 25.613 Material strength properties and design values.

(a) Material strength properties must be based on enough tests of material

meeting approved specifications to establish design values on a statistical basis.

(b) Design values must be chosen to minimize the probability of structural failuresdue to material variability. Except as provided in paragraph (e) of this section,

compliance with this paragraph must be shown by selecting design values which

assure material strength with the following probability:

(1) Where applied loads are eventually distributed through a single member within an

assembly, the failure of which would result in loss of structural integrity of the

component, 99 percent probability with 95 percent confidence.

(2) For redundant structure, in which the failure of individual elements would result in

applied loads being safely distributed to other load carrying members, 90 percent

probability with 95 percent confidence.


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Material strength properties and design values

(c) The effects of temperature on allowable stresses used for designin an essential component or structure must be considered wherethermal effects are significant under normal operating conditions.

(d) The strength, detail design, and fabrication of the structure must

minimize the probability of disastrous fatigue failure, particularly atpoints of stress concentration.

(e) Greater design values may be used if a "premium selection" ofthe material is made in which a specimen of each individual item istested before use to determine that the actual strength propertiesof that particular item will equal or exceed those used in design.


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Design properties

Sec. 25.615 Design properties.

(a) Design properties outlined in MIL-HDBK-5 may be used subject to the following

conditions:

(1) Where applied loads are eventually distributed through a single member within an

assembly, the failure of which would result in the loss of the structural integrity of the

component involved, the guaranteed minimum design mechanical properties ("A"

values) when listed in MIL-HDBK-5 must be met.

(2) Redundant structures, in which the failure of individual elements would result in

applied loads being safely distributed to other load-carrying members, may be designed

on the basis of the "90 percent probability ("B" values)" when listed in MIL-HDBK-5.

(b) Design values greater than the guaranteed minimums required by paragraph (a) of this

section may be used where only guaranteed minimum values are normally allowed if a

"premium selection" of the material is made 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.


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Special factors

Sec. 25.619 Special factors.

The factor of safety prescribed in Sec. 25.303 must bemultiplied by the highest pertinent special factor of safety

prescribed in Secs. 25.621 through 25.625 for each part ofthe structure whose strength is

(a) Uncertain;

(b) Likely to deteriorate in service before normal replacement;or (c) Subject to appreciable variability because of uncertaintiesin manufacturing processes or inspection methods.


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Casting factors

Sec. 25.621 Casting factors.

(a) General. The factors, tests, and inspections specified in paragraphs (b)through (d) of this section must be applied in addition to those necessaryto establish foundry quality control. The inspections must meet approvedspecifications. Paragraphs (c) and (d) of this section apply to any structural

castings except castings that are pressure tested as parts of hydraulic orother fluid systems and do not support structural loads.

(b) Bearing stresses and surfaces. The casting factors specified inparagraphs (c) and (d) of this section

(1) Need not exceed 1.25 with respect to bearing stresses regardless of themethod of inspection used; and

(2) Need not be used with respect to the bearing surfaces of a part whosebearing factor is larger than the applicable casting factor.


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Casting factors (continued)

(c) Critical castings. For each casting whose failure would preclude continued safe flight 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) Receive 100 percent inspection by visual, radiographic, and magnetic particle or

penetrant inspection methods or approved equivalent non-destructive inspectionmethods.

(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 corresponding 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 fittings, parts of flight 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.


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(d) Noncritical castings. For each casting other than those specifiedin paragraph (c) of this section, the following apply:

(1) Except as provided in paragraphs (d) (2) and (3) of this section, thecasting factors and corresponding inspections must meet the followingtable:

Casting factor -> Inspection

2.0 or more -> 100 percent visual.

Less than 2.0 but more than 1.5 -> 100 percent visual, and magnetic particle orpenetrant or equivalent non-destructive inspection methods.

1.25 through 1.50 -> 100 percent visual, magnetic particle or penetrant, andradiographic, or approved equivalent non-destructive inspection methods.


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(2) The percentage of castings inspected by nonvisual methods maybe reduced below that specified in paragraph (d)(1) of this sectionwhen an approved quality control procedure is established.

(3) For castings procured to a specification that guarantees the

mechanical properties of the material in the casting and providesfor demonstration of these properties by test of coupons cut fromthe castings on a sampling basis

(i) A casting factor of 1.0 may be used; and

(ii) The castings must be inspected as provided in paragraph (d)(1) ofthis section for casting factors of "1.25 through 1.50" and tested underparagraph (c)(2) of this section.


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Bearing factors

Sec. 25.623 Bearing factors.

(a) Except as provided in paragraph (b) of thissection, each part that has clearance (free fit),and that is subject to pounding or vibration, musthave a bearing factor large enough to provide forthe effects of normal relative motion.

(b) No bearing factor need be used for a part forwhich any larger special factor is prescribed.


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Fitting factors

Sec. 25.625 Fitting factors. For each fitting (a part or terminal used to join onestructural member to another), the following apply:

(a) For each fitting whose strength is not proven by limit and ultimate load tests inwhich actual stress conditions are simulated in the fitting and surroundingstructures, a fitting factor of at least 1.15 must be applied to each part of-- (1) The fitting;

(2) The means of attachment; and (3) The bearing on the joined members.

(b) No fitting factor need be used-- (1) For joints made under approved practices and based on comprehensive test data (such as

continuous joints in metal plating, welded joints, and scarf joints in wood); or

(2) With respect to any bearing surface for which a larger special factor is used.

(c) For each integral fitting, the part must be treated as a fitting up to the point atwhich the section properties become typical of the member.

(d) For each seat, berth, safety belt, and harness, the fitting factor specified in Sec.25.785(f)(3) applies.


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QUESTIONS AND ANSWERS

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5 asr - airworthiness requirements

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