Source: https://ntsb.gov/investigations/AccidentReports/_layouts/ntsb.recsearch/Recommendation.aspx?Rec=A-91-087
Timestamp: 2019-06-16 07:31:08
Document Index: 21508776

Matched Legal Cases: ['art 25', 'art 25', 'art 25', 'art 25', 'art 23', 'art 25', 'art 25', 'art 25', 'arts 121', 'art 23', 'art 25', 'art 25', 'ART 25', 'ART 25', 'ART 25', 'ARTS 23', 'arts 23', 'ART 25', 'ARTS 23']

Safety Recommendation A-91-087
Recommendation: THE NTSB RECOMMENDS THAT THE FEDERAL AVIATION ADMINISTRATION: AMEND THE ICING CERTIFICATION RULES TO REQUIRE FLIGHT TESTS WHEREIN ICE IS ACCUMULATED IN THOSE CRUISE AND APPROACH FLAP CONFIGURATION IN WHICH EXTENSIVE EXPOSURE TO ICING CONDITIONS CAN BE EXPECTED, AND REQUIRE SUBSEQUENT CHANGES IN CONFIGURATION, TO INCLUDE LANDING FLAPS.
Date Closed: 5/2/2008
Response: On July 25, 2007, the FAA issued a final rule, titled Airplane Performance and Handling Qualities in Icing Conditions, which became effective October 9, 2007. On September 10, 2007, the FAA issued Advisory Circular (AC) 25-25, Performance and Handling Characteristics in the Icing Conditions Specified in Part 25, Appendix C. The AC provides detailed guidance on acceptable means of compliance with the new requirements. The Safety Board reviewed the final rule and related information in the AC and has determined that it fully meets the intent of this recommendation. Consequently, Safety Recommendation A-91-87 is classified Closed Acceptable Action.
Response: Letter Mail Controlled 1/29/2008 11:10:10 AM MC# 2080040: Robert A. Sturgell, Acting Administrator, FAA, 1/22/08 On May 10, 2006, the Board classified this recommendation Open-Acceptable Response pending issuance of the final rule and advisory material for evaluating airplane performance and handling characteristics in icing conditions. The enclosed final rule for Airplane Performance and Handling Qualities in Icing Conditions was issued July 25, 2007 and became effective on October 9, 2007. This final rule applies to transport category airplanes and becomes amendment 121 to 14 Code of Federal Regulations part 25. We also released the enclosed Advisory Circular (AC) 25-25, which provides detailed guidance on acceptable means of compliance with the new part 25 requirements. The final rule and AC also partially address Safety Recommendations A-96-56, A-96-58, and A-98-96. I will update the Board of the FAA's progress on these safety recommendations separately. I believe that the FAA has satisfactorily responded to Safety Recommendation A-91-87, and I look forward to your response.
Response: The Safety Board notes that on November 4, 2005, the FAA issued a notice of proposed rulemaking (NPRM) titled "Airplane Performance and Handling Qualities in Icing Conditions; Proposed Advisory Circular [AC] 25.21-1X, Performance and Handling Characteristics in the Icing Conditions Specified in Part 25, Appendix C." The Board reviewed this large and technically complex NPRM, and separately submitted technical comments to the docket. The NPRM is responsive to this recommendation. This recommendation is now 14 years old, and it is currently the oldest open aviation safety recommendation. The Board believes that issuance of this NPRM was delayed by important lessons learned from several significant icing accidents during the 1990s, each of which revealed new information concerning the icing problem. Before the NPRM was issued, the FAA conducted flight tests of ice contaminated tailplane stall and investigated airplanes with unpowered control systems that had been certificated without such an evaluation. For airplanes susceptible to ice contaminated tailplane stall, the FAA issued airworthiness directives (ADs) to improve tailplane stall margins. Finally, in August 2004, the FAA issued AC 23.1419 2C, "Certification of Part 23 Airplanes for Flight in Icing." The Board is pleased to see that the NPRM has been issued, and we urge the FAA to move quickly to issue the final rule. Pending issuance of a final rule revising sections of Part 25 regulations and advisory material for evaluating airplane performance and handling characteristics in icing conditions, Safety Recommendation A-91-87 remains classified "Open-Acceptable Response." Safety Recommendations A-96-54, -56, and -58 were issued to the FAA as a result of the Safety Board's investigation of an October 31, 1994, accident in which American Eagle flight 4184, an Avions de Transport Regional Model 72-212 (ATR 72-212), crashed during a rapid descent after an uncommanded roll excursion in icing conditions over Roselawn, Indiana.
Response: The National Transportation Safety Board has reviewed the Federal Aviation Administration (FAA) notice of proposed rulemaking (NPRM), Airplane Performance and Handling Characteristics in Icing Conditions, published in the Federal Register (Vol. 70, No. 213) on November 4, 2005. The Safety Board has evaluated the NPRM, which applies to newly certificated designs, in light of current, open recommendations related to aircraft icing and in regard to other concerns identified during the course of its investigations. Previous Icing Certification Recommendations The Safety Board has been concerned for many years about the inadequacy of the existing certification regulations for flight in icing conditions, which have not required manufacturers to demonstrate an airplane's flight handling, stall characteristics, minimum airspeeds, and stall margins under a sufficiently realistic range of adverse ice accretions. Additionally, the regulations have not required airplanes to be tested with the thin, rough ice that can accrete on protected surfaces prior to the activation of ice protection systems or between activation cycles of the ice protection systems, especially in larger water droplet environments. These issues came to light during the Board's investigations of two accidents involving loss of control in icing conditions: United Express flight 2415, a British Aerospace BA-3101, in Pasco, Washington (December 26, 1989), and COMAIR flight 3272, an Embraer EMB-120RT, in Monroe, Michigan (January 9, 1997). United Express flight 2415 involved an ice-contaminated tailplane stall and loss of control at low altitude. Contributing to the loss of control was the accumulation of ice on the airframe, which degraded the aerodynamic performance of the airplane. The United Express 2415 investigation resulted in Safety Recommendation A-91-87: Amend the icing certification rules to require flight tests wherein ice is accumulated in those cruise and approach flap configurations in which extensive exposure to icing conditions can be expected, and require subsequent changes in configuration, to include landing flaps. [Status: "Open-Acceptable Response"] Several years later, the Safety Board investigated the Comair 3272 accident, which involved a loss of control while the airplane was maneuvering with ice accretions on the wings. The Safety Board determined that the probable cause of the accident was the following: The FAA's failure to establish adequate aircraft certification standards for flight in icing conditions ... and the FAA's failure to require the establishment of adequate minimum airspeeds for icing conditions, which led to the loss of control when the airplane accumulated a thin, rough accretion of ice on its lifting surfaces.
Response: Letter Mail Controlled 10/27/2005 2:12:40 PM MC# 2050501 Marion C. Blakey, Administrator, FAA, 10/26/05 The Federal Aviation Administration is continuing its efforts to revise the 14 CFR Part 25 requirements and related advisory material to introduce new requirements for evaluating airplane performance and handling characteristics of transport-category airplanes for flight in the icing conditions of 14 CFR Part 25, Appendix C. There has been a delay in the publication of these documents and it is now anticipated that they will be published for comment by October 2005. Although the proposed notice of proposed rulemaking (NPRM) and advisory circular (AC) have been delayed, the FAA has been responsive to the safety issue addressed in this safety recommendation. The FAA has been conducting flight test evaluations for susceptibility to ice-contaminated tailplane stall for all airplanes approved for flight in icing conditions since the mid-1990s. The FAA has also investigated airplanes with unpowered control systems operating under 14 CFR Parts 121 and 135 operating rules that had been certificated without such an evaluation. For those airplanes found to be susceptible to ice-contaminated tailplane stall, the FAA mandated changes through airworthiness directives (AD) to improve tailplane stall margins. Also, AC 23.1419-2C, Certification of Part 23 Airplanes for Flight in Icing, was issued in August 2004 and guidance on ice accretions in the landing configuration has been added. The proposed NPRM will provide a comprehensive set of new certification requirements to evaluate airplane performance and handling characteristics in icing conditions in order to improve the level of safety for operation in icing conditions. One of the proposed certification requirements will be to conduct a flight test maneuver that is designed to evaluate airplanes for susceptibility to ice-contaminated tailplane stall. This evaluation takes into account lessons learned from analyses of icing accidents that have occurred sincc the accident that generated this safety recommendation. Therefore, it will address more potential causes of ice-contaminated tailplane stall than the single concern identified in this safety recommendation. In addition to the concern identified in the safety recommendation, this evaluation considers changes in flight conditions (for example, a high approach speed resulting in an increased flap downwash angle, gusts, maneuvering, or changes to engine power setting, as well as lateral airflow effects like a sideslip or a lateral wind gust). An accompanying AC will provide detailed guidance on acceptable means of compliance with the new requirements. The proposed AC will include several flight test maneuver conditions with ice being progressively accreted while the airplane configuration changes from flaps and gear retracted with the airplane trimmed at the recommended holding speed to flaps and gear fully extended with the airplane trimmed at the landing reference speed. I will provide the Board with copies of the NPRM and AC as soon as they are published for comment.
Response: The Safety Board is pleased that the FAA is responding positively to this recommendation, but feels compelled to note that it has been 11 1/2 years since it was issued. The Board is aware that several prominent aviation accidents occurred during the 1990s in which icing was a factor and from which important lessons were learned. The Board believes that analyses of these accidents should result in a more complete response to this recommendation. Pending publication of the NPRM by June 2004 and adoption of a final rule, Safety Recommendation A-91-87 remains classified "Open--Acceptable Response."
Response: Letter Mail Controlled 5/13/2003 10:57:31 AM MC# 2030238 The Aviation Rulemaking Advisory Committee has drafted recommended changes to 14 CFR Part 25 requirements and related advisory material to introduce new requirements for evaluating airplane performance and handling characteristics of transport-category airplanes for flight in the icing conditions of 14 CFR Part 25, Appendix C. The Federal Aviation Administration (FAA) will publish a notice of proposed rulemaking (NPRM) based on these recommendations. It is anticipated that the NPRM will be issued by June 2004. The recommendations include a proposed regulatory amendment that contains a flight test maneuver to evaluate airplanes for susceptibility to ice-contaminated tailplane stall. The advisory material provides detailed flight test guidance, including consideration of critical ice accretions that may be accumulated during extensive exposure to icing conditions, and evaluated in the most critical landing configurations. I will keep the Board informed on the FAA's progress on this safety recommendation.
Response: THE SAFETY BOARD IS CONCERNED ABOUT THE LENGTH OF TIME IT HAS TAKEN TO COMPLETE WORK ON THIS RECOMMENDATION. THE BOARD NOTES THAT IT HAS BEEN ABOUT 9 YEARS SINCE THIS RECOMMENDATION WAS ISSUED. HOWEVER, THE BOARD ALSO NOTES THAT SEVERAL PROMINENT AVIATION ACCIDENTS OCCURRED DURING THE 1990'S IN WHICH ICING WAS AN IMPORTANT CONSIDERATION AND FROM WHICH IMPORTANT INFORMATION WAS LEARNED. THEREFORE, ALTHOUGH THE BOARD UNDERSTANDS THE REASONS FOR THE DELAY IN COMPLETING THIS WORK, THE BOARD ALSO BELIEVES THAT THE FAA SHOULD COMPLETE THIS WORK SOON. PENDING AMENDMENT OF THE ICING CERTIFICATION RULES, A-91-87 REMAINS CLASSIFIED "OPEN--ACCEPTABLE RESPONSE."
Response: Letter Mail Controlled 09/01/2000 1:25:45 PM MC# 2001200 ON 4/29/94, THE FAA ISSUED A POLICY MEMORANDUM TO ALL CERTIFICATION OFFICES DESCRIBING THE TAILPLANE STALL PHENOMENON AND DEFINING A FLIGHT TEST MANEUVER (ZERO-G PUSHOVER MANEUVER) TO IDENTIFY SUSCEPTIBILITY TO ICE-CONTAMINATED TAILPLANE STALL. ON 3/31/98, THE FAA ISSUED ADVISORY CIRCULAR (AC) 25-7, FLIGHT TEST GUIDE FOR CERTIFICATION OF TRANSPORT CATEGORY AIRPLANES. THE AC INCLUDES GUIDANCE MATERIAL DEFINING ZERO-G PUSHOVER MANEUVER FOR SHOWING COMPLIANCE WITH 14 CFR 25.143, CONTROLLABILITY AND MANEUVERABILITY. COPIES OF THE POLICY MEMORANDUM AND THE AC WERE PROVIDED TO THE BOARD. THE FLIGHT TEST HARMONIZATION WORKING GROUP HAS NOW COMPLETED THE TECHNICAL CONTENT OF PROPOSED 14 CFR PART 25 REGULATIONS AND ADVISORY MATERIAL FOR EVALUATING AIRPLANE PERFORMANCE AND HANDLING CHARACTERISTICS IN THE ICING CONDITIONS OF APPENDIX C AND IS CURRENTLY DEVELOPING ITS PROPOSALS. THESE PROPOSALS INCLUDE A REQUIREMENT TO INVESTIGATE AIRPLANE SUSCEPTIBILITY TO ICE-CONTAMINATED TAILPLANE STALL. THE FAA WILL PUBLISH A NOTICE OF PROPOSED RULEMAKING (NPRM) AFTER THE ARAC COMPLETES ITS WORK. IT IS ANTICIPATED THAT THE NPRM WILL BE PUBLISHED IN EARLY 2002. I WANT TO EMPHASIZE THAT UNTIL THE RULEMAKING EFFORT IS COMPLETED, THE FAA WILL REVIEW EACH SIGNIFICANT PROJECT RELATED TO ICING TO ENSURE THROUGH THE PROVISIONS OF 14 CFR 21.21(B)(2) THAT NO UNSAFE CONDITION EXISTS. I WILL KEEP THE BOARD INFORMED OF THE FAA'S PROGRESS ON THIS RECOMMENDATION.
Response: THE BOARD NOTES THE CHANGES IN AC 25-7A AS THEY PERTAIN TO FLIGHT TESTING IN ICING CONDITIONS. THESE CHANGES OFFER GUIDANCE IN TESTING FLIGHT OPERATIONS IN ICING CONDITIONS, AND THE EXPECTED NEW RULES THAT MAY RESULT FROM THE ACTIONS OF THE ARAC PROCESS SHOULD PROVIDE UPDATED GUIDANCE IN THIS CRITICAL FIELD. A-91-87 IS CLASSIFIED "OPEN--ACCEPTABLE RESPONSE," PENDING THE ACTIONS OF THE ARAC EFFORT.
Response: Letter Mail Controlled 02/19/1999 10:03:45 AM MC# 981470 ON 4/29/94, THE FAA ISSUED A POLICY MEMORANDUM TO ALL CERTIFICATION OFFICES DESCRIBING THE TAILPLANE STALL PHENOMENA AND DEFINING A FLIGHT TEST MANEUVER (ZERO-G PUSHOVER MANEUVER) TO IDENTIFY SUSCEPTIBILITY TO ICE CONTAMINATED TAILPLANE STALL. ON 3/31/98, FAA ISSUED ADVISORY CIRCULAR (AC) 25-7, FLIGHT TEST GUIDE FOR CERTIFICATION OF TRANSPORT CATEGORY AIRPLANES. THE AC INCLUDES GUIDANCE MATERIAL ON ZERO-G PUSHOVER MANEUVER FOR COMPLIANCE WITH 14 CFR 25.143, CONTROLLABILITY AND MANEUVERABILITY. I HAVE ENCLOSED A COPY OF THE AC FOR THE BOARD'S INFORMATION. AN AVIATION RULEMAKING ADVISORY COMMITTEE (ARAC) PROJECT TO HARMONIZE REGULATORY AND ADVISORY MATERIAL FOR EVALUATING AIRPLANE PERFORMANCE AND HANDLING CHARACTERISTICS IN THE ICING CONDITIONS OF APPENDIX C TO 14 CFR PART 25 WILL ALSO ADDRESS THE TAILPLANE STALL ISSUE. THE RESULTS OF THE ARAC EFFORT WILL BE PUBLISHED AS NEW REGULATIONS AND ADVISORY MATERIAL.
Response: THE BOARD NOTES THAT ON 4/29/94, THE FAA ISSUED A POLICY MEMORANDUM TO ALL CERTIFICATION OFFICES DESCRIBING THE TAILPLANE STALL PHENOMENA & DEFINING A FLIGHT TEST MANEUVER (ZERO-G PUSHOVER MANEUVER) TO IDENTIFY SUSCEPTIBILITY TO ICE-CONTAMINATED TAILPLANE STALL. THE BOARD ALSO NOTES THAT THIS INTERIM GUIDANCE MAY BE INCLUDED IN A PROPOSED REVISION TO ADVISORY CIRCURLAR 25-7, "FLIGHT TEST GUIDE FOR CERTIFICATION OF TRANSPORT CATEGORY AIRPLANES." ALSO, A "TERMS OF REFERENCE" DOCUMENT HAS BEEN DRAFTED & HAS BEEN SUBMITTED TO THE AVIATION RULEMAKING ADVISORY COMMITTEE FOR REVIEW & HARMONIZATION OF ICE PROTECTION STANDARDS FOR TRANSPORT-CATEGORY AIRPLANES. PENDING THE BOARD'S REVIEW OF THE REVISION TO AC 25-7, & THE FAA'S REVIEW OF APPENDIX C OF 14 CFR PART 25 & ANY RULEMAKING TO REVISE PARTS 23 & 25, A-91-87 IS CLASSIFIED "OPEN--ACCEPTABLE ALTERNATE RESPONSE."
Response: ON 4/29/94, THE FAA ISSUED A POLICY MEMORANDUM TO ALL CERTIFICATION OFFICES DESCRIBING THE TAILPANE STALL PHENOMENA & DEFINING A FLIGHT TEST MANEUVER (ZERO-G PUSHOVER MANEUVER) TO IDENTIFY SUSCEPTIBILITY TO ICE CONTAMINATED TAILPLANE STALL. THIS INTERIM GUIDANCE IS BEING CONSIDERED FOR INCLUSION IN A PROPOSED REVISION TO ADVISORY CIRCULAR 25-7, FLIGHT TEST GUIDE FOR CERTIFICATION OF TRANSPORT CATEGORY AIRPLANES.
Response: In response to Safety Recommendation A-91-87, which asked the FAA to amend icing certification rules, we note that the FAA will publish advisory material to address icing certification procedures for 14 CFR Parts 23 and 25 category airplanes. Although the Safety Board does not agree that the current language in 14 CFR 25.1419 specifically addresses the change of configuration following the accumulation of ice, the inclusion of this certification procedure in an appropriate document, such as the Engineering Flight Test Guide, may satisfy the Safety Board's concern. Thus, pending our further review, this safety recommendation is classified as "Open- Acceptable Alternate Response."
Response: THE FAA BELIEVES THAT THE CURRENT CERTIFICATION REQUIREMENTS OF 14 CFR 25.1419 CONTAIN THE STANDARDS REQUESTED BY THIS SAFETY RECOMMENDATION. SECTION 25.1419 (B) STATES, IN PART, THAT THE AIRPLANE OR ITS COMPONENTS MUST BE FLIGHT TESTED IN THE VARIOUS OPERATIONAL CONFIGURATIONS IN MEASURED NATURAL ATMOSPHERIC ICING CONDITIONS IN ACCORDANCE WITH APPENDIX C. THE REGULATIONS ALSO DESCRIBE OTHER TESTS THAT MUST BE PERFORMED "AS FOUND NECESSARY ." ADDITIONALLY THE FAA BELIEVES THAT SINCE THE ICING CERTFICATION RULES UNDER 14 CFR 23.1419 (B) REFER TO APPENDIX C OF 14 CFR PART 25, THESE REGULATIONS ADEQUATELY ADDRESS THE ICING CERTIFICATION REQUIREMENTS. AS AN ALTERNATE ACTION, THE FAA WILL PUBLISH ADVISORY MATERIAL TO ADDRESS ICING CERTIFICATION PROCEDURES FOR 14 CFR PARTS 23 25 CATEGORY AIRPLANES.