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A separate sheet for the “ICA” is a necessary part of every 337 submission. It should include a section for each of the following items, even if only to list “Not Applicable”

Introduction: This section briefly describes the aircraft, engine, propeller, or component that has been altered. Include any other information on the content, scope, purpose, arrangement, applicability, definitions, abbreviations, precautions, units of measurement, referenced publications, and distribution of the ICA as applicable.

Description: Of the major alteration, its functions, including an explanation of its interface with other systems, if any

Control: Operation information: Or special procedures, if any.

Servicing information: Such as types of fluids used, servicing points, and location of access panels, as appropriate

Maintenance Instructions: Such as recommended inspection/maintenance periods in which each of the major alteration components are inspected, cleaned, lubricated, adjusted, tested, including applicable wear tolerances and work recommended at each scheduled maintenance period. This section can refer to the manufacturers’ instructions for the equipment installed where appropriate (e.g., functional checks, repairs, inspections.) It should also include any special notes, cautions, or warnings, as applicable.

Trouble shooting information: Information describing probable malfunctions, how to recognize those malfunctions, and the remedial actions to be taken.

Removal and replacement information: This section describes the order and method of removing and replacing products, parts and any necessary precautions. This section should also describe or refer to manufacturer’s instructions to make required tests, trim checks, alignment, calibrations, center of gravity changes, lifting or shoring, etc., if any.

Diagrams: Of access plates and information, if needed, to gain access for inspection.

Special inspection requirements: Such as X-ray, ultrasonic testing, or magnetic particle inspection, if required. 

Application of protective treatments: To the affected area after inspection and/or maintenance, if any.

Data: Relative to structural fasteners such as type, torque, and installation requirements, if any.

List of special tools: Special tools that are required, if any.

Recommended overhaul periods: Are required to be noted on the ICA when an overhaul period has been set by the manufacturer of a component, or equipment. If there is no overhaul period, the ICA should state for item 14: “No additional overhaul time limitations.”

Airworthiness Limitation Section: Include any “approved” airworthiness limitations identified by the manufacturer or FAA Type Certificate Holding Office (e.g., An STC incorporated in a larger field approved major alteration may have an airworthiness limitation.) The FAA inspector should not establish, alter, or cancel airworthiness limitations without coordinating with the appropriate FAA Type Certificate Holding Office. If there are no changes to the airworthiness limitations, the ICA should state for item 15: “No additional airworthiness limitations” or “Not Applicable.”

Revision: This section should include information on how to revise the ICA. For example, a letter will be submitted to the local FSDO with a copy of the revised FAA Form 337 and revised ICA. The FAA inspector accepts the change by signing Block 3 and including the following statement: “The attached revised/new Instructions for Continued Airworthiness (date______) for the above aircraft or component major alteration have been accepted by the FAA, superseding the Instructions for Continued Airworthiness (date______).” Once the revision has been accepted, a maintenance record entry will be made, identifying the revision, its location, date of the Form 337.


Implementation and Record Keeping: For major alterations performed in accordance with FAA Field Approval policy, the owner/operator operating under part 91 is responsible for ensuring that the ICA is made part of the applicable section 91.409 inspection program for their aircraft. This is accomplished when a maintenance entry is made in the aircraft’s maintenance record in accordance with section 43.9. This entry records the major alteration and identifies the original ICA location (e.g., Block 8 of FAA Form 337, dated 5/28/98) along with a statement that the ICA is now part of the aircraft’s inspection/maintenance requirements.