AD 2000-04-03

This amendment adopts a new airworthiness directive (AD), applicable to certain McDonnell Douglas Models DC-3 and DC-4 series airplanes that requires an inspection to determine the type of airframe pneumatic deicing boots installed. This amendment also requires revising the Airplane Flight Manual (AFM) to include requirements for activation of the pneumatic deicing boots for those airplanes equipped with "modern" boots. This amendment is prompted by reports of inflight incidents and an accident that occurred in icing conditions where the airframe pneumatic deicing boots were not activated. The actions specified by this AD are intended to ensure that flightcrews activate the pneumatic wing and tail deicing boots at the first signs of ice accumulation. This action will prevent reduced controllability of the aircraft due to adverse aerodynamic effects of ice adhering to the airplane prior to the first deicing cycle.

Final rule

2000-04-03 MCDONNELL DOUGLAS: Amendment 39-11585. Docket 99-NM-139-AD. \n\n\tApplicability: Models DC-3 and DC-4 series airplanes equipped with pneumatic deicing boots, certificated in any category. \n\n\tCompliance: Required as indicated, unless accomplished previously. \n\n\tTo ensure that flightcrews activate the wing and tail pneumatic deicing boots at the first signs of ice accumulation on the airplane, accomplish the following: \n\n\tNOTE 1: For the purposes of this AD, the following definitions of "older" and "modern" apply: \n\n\t"Modern" pneumatic boot systems may be characterized by short segmented, small diameter tubes, which are operated at relatively high pressures (18-23 pounds per square inch (psi)) by excess bleed air that is provided by turbine engines. "Older" pneumatic boot systems may be characterized by long, uninterrupted, large diameter tubes, which were operated at low pressures by engine driven pneumatic pumps whose pressure varied with engine revolutions per minute (rpm). This low pressure coupled with long and large diameter tubes caused early de-ice systems to have very lengthy inflation and deflation cycles and dwell times. (Dwell time is the period of time that the boot remains fully expanded following the completion of the inflation cycle until the beginning of the deflation cycle.) \n\n\t(a)\tWithin 10 days after the effective date of this AD: Perform a visual inspection to determine if the type of pneumatic deicing boots installed is either "older" or "modern" boots. \n\n\tNOTE 2: For the purposes of this AD, a detailed visual inspection is defined as: "An intensive visual examination of a specific structural area, system, installation, or assembly to detect damage, failure, or irregularity. Available lighting is normally supplemented with a direct source of good lighting at intensity deemed appropriate by the inspector. Inspection aids such as mirror, magnifying lenses, etc., may be used. Surface cleaning and elaborate access procedures may be required." \n\n\t\t(1)\tFor those airplanes equipped with "older" pneumatic deicing boots, no further action is required by this AD. \n\n\t\t(2)\tFor those airplanes equipped with "modern" pneumatic deicing boots, within 10 days after the inspection required by paragraph (a) of this AD: Revise the Limitations Section of the FAA-approved Airplane Flight Manual (AFM) to include the following requirements for activation of the ice protection systems. This may be accomplished by inserting a copy of this AD in the AFM. \n\n\t" Except for certain phases of flight where the AFM specifies that deicing boots should not be used (e.g., take-off, final approach, and landing), compliance with the following is required.\n \n\t Wing and Tail Leading Edge Pneumatic Deicing Boot System, if installed, must be activated: \n\n\t\t- At the first sign of ice formation anywhere on the aircraft, or upon annunciation from an ice detector system, whichever occurs first; and \n\n\t\t- The systemmust either be continued to be operated in the automatic cycling mode, if available; or the system must be manually cycled as needed to minimize the ice accretions on the airframe. \n\n\t The wing and tail leading edge pneumatic deicing boot system may be deactivated only after leaving icing conditions and after the airplane is determined to be clear of ice." \n\nAlternative Methods of Compliance \n\t(b)\tAn alternative method of compliance or adjustment of the compliance time that provides an acceptable level of safety may be used if approved by the Manager, Los Angeles Aircraft Certification Office, Transport Airplane Directorate. The request shall be forwarded through an appropriate FAA Operations Inspector, who may add comments and then send it to the Manager, Los Angeles ACO. \n\n\tNOTE 3: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Los Angeles ACO. \n\nSpecial Flight Permits \n\t(c)\tSpecial flight permits may be issued in accordance with sections 21.197 and 21.199 of the Federal Aviation Regulations (14 CFR 21.197 and 21.199) to operate the airplane to a location where the requirements of this AD can be accomplished. \n\n\t(d)\tThis amendment becomes effective on March 28, 2000.

A proposal to amend part 39 of the Federal Aviation Regulations (14 CFR part 39) to include an airworthiness directive (AD) that is applicable to certain McDonnell Douglas Models DC-3 and DC-4 series airplanes was published as a supplemental notice of proposed rulemaking (NPRM) in the Federal Register on November 18, 1999 (64 FR 62993). That action proposed to require an inspection to determine the type of airframe pneumatic deicing boots installed. That action also proposed to require revising the Airplane Flight Manual (AFM) to include requirements for activation of the pneumatic deicing boots for those airplanes equipped with "modern" boots. \n\nComments \n\tInterested persons have been afforded an opportunity to participate in the making of this amendment. No comments were submitted in response to the proposal or the FAA's determination of the cost to the public. \n\nAddition of Note 2 \n\tThe FAA has added a new Note 2 that provides an explanation ofthe term "visual inspection" as specified in paragraph (a) of the final rule. \n\nConclusion \n\tAfter careful review of the available data, the FAA has determined that air safety and the public interest require the adoption of the rule with the changes previously described. The FAA has determined that these changes will neither increase the economic burden on any operator nor increase the scope of the AD. \n\nCost Impact \n\tThe FAA estimates that 166 airplanes of U.S. registry will be affected by this AD. \n\n\tThe FAA estimates that it will take approximately 2 work hours per airplane to accomplish the required actions, at the average labor rate of $60 per work hour. Based on these figures, the cost impact of this AD on U.S. operators is estimated to be $19,920, or $120 per airplane. \n\n\tThe cost impact figure discussed above is based on assumptions that no operator has yet accomplished any of the requirements of this AD action, and that no operator would accomplish those actions in the future if this AD were not adopted. \n\nRegulatory Impact \n\tThe regulations adopted herein will not have a substantial direct effect on the States, on the relationship between the national Government and the States, or on the distribution of power and responsibilities among the various levels of government. Therefore, it is determined that this final rule does not have federalism implications under Executive Order 13132. \n\n\tFor the reasons discussed above, I certify that this action (1) is not a "significant regulatory action" under Executive Order 12866; (2) is not a "significant rule" under DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979); and (3) will not have a significant economic impact, positive or negative, on a substantial number of small entities under the criteria of the Regulatory Flexibility Act. A final evaluation has been prepared for this action and it is contained in the Rules Docket. A copy of it may be obtained from the Rules Docketat the location provided under the caption "ADDRESSES." \n\nList of Subjects in 14 CFR Part 39 \n\tAir transportation, Aircraft, Aviation safety, Safety. \n\nAdoption of the Amendment \n\tAccordingly, 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:\n\nPART 39 - AIRWORTHINESS DIRECTIVES \n\t1. The authority citation for part 39 continues to read as follows:\nAuthority: 49 U.S.C. 106(g), 40113, 44701. \n\n§ 39.13 (Amended) \n\t2. Section 39.13 is amended by adding the following new airworthiness directive: