Events Leading to the Issuance of This AD
What caused this AD?
This AD is the result of reports of in-flight incidents and an accident (on airplanes other than the affected Pilatus airplanes) that occurred in icing conditions where the airframe pneumatic deicing boots were not activated. The Pilatus Models PC-12 and PC-12/45 airplanes have a similar type design (as it relates to airframe pneumatic ice boots) to the incident and accident airplanes.
What is the potential impact if FAA took no action?
The information necessary to activate the pneumatic wing and tail deicing boots at the first signs of ice accumulation is critical for flight in icing conditions. If we did not take action to include this information, flight crews could experience reduced controllability of the aircraft due to adverse aerodynamic effects of ice adhering to the airplane prior to the first deicing cycle.
Has FAA taken any action to this point?
We issued a proposal to amend part 39 of the Federal Aviation Regulations (14 CFR part 39) to include an AD that would apply to all Pilatus Models PC-12 and PC-12/45 airplanes that are equipped with pneumatic deicing boots. This proposal published in the Federal Register as a notice of proposed rulemaking (NPRM) on October 8, 1999 (64 FR 54833). The NPRM proposed to require revising the Limitations Section of the AFM to include requirements for activation of pneumatic deicing boots at the first indication of ice accumulation on the airplane.
Was the public invited to comment?
The FAA invited interested persons to participate in the making of this amendment. Following is a summary of the two comments received with FAA's response.
Comment Issue No. 1: Allow the Use of Recent Airplane Flight Manual (AFM) Additions
What is the Commenter's Concern?
Pilatus requests that FAA allow the operators of the affected airplanes to use as an alternative method of compliance the most recent information forSection 2, Limitations, of the Pilatus PC12 Airplane Flight Manual (AFM). This information is included in Report No.: 01973-001, page 2-12, Revision 9: September 1, 1999, and includes the following language:
"The wing and tail leading edge pneumatic deicing boot system must be activated at the first sign of ice formation anywhere on the aircraft, or upon annunciation from an ice detector system (if installed), whichever occurs first.
The wing and tail leading edge pneumatic deicing boot system may be deactivated only after leaving icing conditions and after the aircraft is determined to be clear of ice."
What is FAA's Response to the Concern?
We have determined that inserting this report into the Section 2, Limitations, of the Pilatus PC12 AFM provides an equivalent level of safety to the actions included in the NPRM. Therefore, we are changing the AD to include the option of incorporating into the AFM the information proposed in the NPRM or Report No.: 01973-001, page 2-12, Revision 9: September 1, 1999.
Comment Issue No. 2: Information is Already Included in the Normal Procedures Section of the AF
What are the Commenter's Concerns?
The Federal Office for Civil Aviation (FOCA), which is the airworthiness authority for Switzerland, believes that the intent of this AD is already covered in the Pilatus PC12 AFM. The FOCA's concerns are as follows:
1. The appropriate time to activate the pneumatic deice boots on the affected Pilatus airplanes is prior to entry into icing conditions, and until the airfoils are free of ice after exiting icing conditions. This information is included in Section 4.10 (Normal Procedures) of the PC12 AFM;
2. These instructions are not necessary in the Limitations Section of the AFM. The Limitations Section should only include limitations relating to speeds, environment (temperatures), or system functions (time limits or configurations). Guidance for this is in FAA Advisory Circular (AC) 25.1419-1, dated August 18, 1999. Paragraph 12(b)(2) of this AC identifies the Procedures Section as the proper place for information "...when the ice protection system should be activated."
The FOCA requests FAA withdraw the NPRM.
What is FAA's Response to the Concerns?
We concur that the information is currently in the Normal Procedures section of the Pilatus PC12 AFM and that previous guidance (advisory circulars) provides information for putting this information in such a section. However, section 91.9 of the Federal Aviation Regulations (14 CFR 91.9) only mandates the operating limitations (Limitations Section): "no person may operate a civil aircraft without complying with the operating limitations specified in the approved Airplane or Rotorcraft Flight Manual."
Based upon the importance of operating the deice boots at the appropriate time, we determined that the information is mandatory. The only method FAA has of changing the Limitations Section of an AFM is through AD action, provided an unsafe condition is demonstrated.
Therefore, we do not concur that the NPRM should be withdrawn. We are not changing the AD as a result of this comment.
The FAA's Determination
What is FAA's final determination on this issue?
After careful review of all available information related to the subject presented above, we have determined that air safety and the public interest require the adoption of the rule as proposed except for the following:
--Including the option of incorporating Report No.: 01973-001, page 2-12, Revision 9: September 1, 1999, into Section 2, Limitations, of the Pilatus PC12 AFM; and
--Minor editorial corrections.
How does including this option and the minor editorial corrections affect the AD?
We have determined that including the AFM option and the minor corrections will not change the meaning of the AD and will not add any additional burden upon the public than was already proposed.
Cost Impact
How many airplanes doesthis AD impact?
We estimate that this AD affects 100 airplanes in the U.S. registry.
What is the cost impact of the affected airplanes on the U.S. Register?
There is no dollar cost impact. We estimate 1 workhour for you to insert the AFM revision. You can accomplish this action if you hold at least a private pilot certificate as authorized by section 43.7 of the Federal Aviation Regulations (14 CFR 43.7). You must make an entry into the aircraft records that shows compliance with this AD, in accordance with section 43.9 of the Federal Aviation Regulations (14 CFR 43.9). Therefore, the only cost impact of this AD is the time it will take you to insert the information into the AFM.
Regulatory Impact
The 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.
For 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 copy of the final evaluation prepared for this action is contained in the Rules Docket. A copy of it may be obtained by contacting the Rules Docket at the location provided under the caption "ADDRESSES".
List of Subjects in 14 CFR Part 39
Air transportation, Aircraft, Aviation safety, Safety.
Adoption of the Amendment
Accordingly, under 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. FAA amends Section 39.13 is amended by adding a new airworthiness directive (AD) to read as follows: