AD 98-05-14 R1

Discussion On February 24, 1998, the FAA issued AD 98-05-14, Amendment 39-10375 (63 FR 10519, March 4, 1998), which applies to Cessna Models T210N, P210N, and P210R airplanes. AD 98-05-14 was the result of a review of the requirements for certification of these airplanes in icing conditions, new information on the icing environment, and icing data provided currently to the flight crew.

AD 98-05-14 requires revising the Limitations Section of the FAA-approved Airplane Flight Manual (AFM) to specify procedures that would:

Require flight crews to immediately request priority handling from Air Traffic Control to exit severe icing conditions (as determined by certain visual cues);

Prohibit flight in severe icing conditions (as determined by certain visual cues);

Prohibit use of the autopilot when ice is formed aft of the protected surfaces of the wing, or when an unusual lateral trim condition exists; and

Require that all icing wing inspection lights be operative prior to flight into known or forecast icing conditions at night.

That action also requires revising the Normal Procedures Section of the FAA-approved AFM to specify procedures that would:

Limit the use of the flaps and prohibit the use of the autopilot when ice is observed forming aft of the protected surfaces of the wing, or if unusual lateral trim requirements or autopilot trim warnings are encountered; and

Provide the flight crew with recognition cues for, and procedures for exiting from, severe icing conditions.

Need for the Correction The AD incorrectly states in paragraph (a)(2) of AD 98-05-14 that: Operation with flaps extended can result in a reduced wing angle-of-attack, with the possibility of ice forming on the lower surface further aft on the wing than normal, possibly aft of the protected area. The word "lower" in this sentence should be "upper."

This incorrect statement may result in pilot misinterpretation of the icing effects with the flaps extended and lead to an incorrect action. The pilot of the affected airplanes can only see the lower wing surface. However, ice accretion on the upper surface of the wing, which the pilot cannot observe, is usually accompanied by ice accretion on the lower surface. As stated earlier, the pilot can observe ice accretion on the lower surface.

Extension of flaps that results in a reduced angle-of-attack can change the relationship of the extent of ice on the upper and lower surfaces of the wing. For example, ice will tend to accrete more on the upper surface than on the lower surface at a reduced angle-of-attack. However, when flaps are extended in certain icing conditions, the reduction of ice further aft on the lower surface of the wing may lead the pilot to conclude incorrectly that there is a reduction of ice further aft on the upper surface. This is not correct; as stated earlier, the tendency is for more ice accretion on the upper surface. Usually, iceon the upper surface of the wing is more adverse to the aerodynamic characteristics of the airplane than is ice on the lower surface of the wing.

Consequently, the FAA saw a need to clarify AD 98-05-14 to assure that this visual cue can be followed and that the appropriate cause and effect relationship is described.

Correction of Publication This document clarifies the intent of the previously discussed visual cue in paragraph (a)(2) of AD 98-05-14. This document also adds the amendment to section 39.13 of the Federal Aviation Regulations (14 CFR 39.13).

Since this action only clarifies the description of a visual cue in AD 98-05-14, it has no adverse economic impact and imposes no additional burden on any person than would have been necessary by the existing AD. Therefore, the FAA has determined that prior notice and opportunity for public comment are unnecessary.

List of Subjects in 14 CFR Part 39 Air transportation, Aircraft, Aviation safety, Safety.

Adoptionof the Amendment Accordingly, pursuant to the authority delegated to me by the Administrator, the Federal Aviation Administration amends part 39 of the Federal Aviation Regulations (14 CFR part 39) as follows:

PART 39 - AIRWORTHINESS DIRECTIVES 1. The authority citation for part 39 continues to read as follows: Authority: 49 U.S.C. 106(g), 40113, 44701.

39.13 [Amended] 2. Section 39.13 is amended by removing Airworthiness Directive (AD) 98-05-14, Amendment 39-10375 (63 FR 10519, March 4, 1998), and by adding a new AD to read as follows: