Turbojet, turboprop, and turbofan engine induction system icing and ice ingestion

Original publisher: [Washington, D.C.]: U.S. Dept. of Transportation, Federal Aviation Administration, [2004]. OCLC Number: (OCoLC)263168544 Subject: Airplanes -- Ice prevention. Excerpt: ... 2 / 02 / 04 AC 20-147 ( 5 ) Disposition of Damage. Disposition of damage to any engine or engine component may not be obtainable solely by comparing the damage against the maintenance manual limits. The cumulative damage for repeated encounters should be evaluated. ( 6 ) Communication of results. The Installation and Operating Manuals required by § 33.5 should provide information describing any resultant engine condition observed during engine certification icing tests. The engine manufacturer should provide a process to permit disposition of any potential damage that could occur during natural icing flight tests conducted to demonstrate compliance with § § 23.1093 or 25.1093, if the installing FAA Aircraft Certification Office finds this acceptable. Also, if periodic engine power run-ups are necessary to minimize damage from icing during the ground icing operation demonstration of § 33.68 ( b ), then this run-up must be documented. Documentation must contain a description of the run-up requirements and the required run-up intervals and it must be contained in the operating manual and airworthiness limitations section of the instructions for continued airworthiness ( ICA ). Any power loss anomalies due to accumulation, shed, runback and the like, and their effects on performance and operation should be documented in the Installation Manual. Both the engine certifying ACO and the installing ACO should carefully consider any high vibrations induced from ice accretions during ice testing. This too should be documented as described above. c. Engine systems. It is permissible to use engine systems ( that is, automatic, engine initiated ice protection systems ) to fulfill § 33.68 requirements provided that its operation is not expected to result in crew action. Examples of engi...