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Safety Recommendation Details

Safety Recommendation A-96-144
Details
Synopsis: ON 8/21/95, ABOUT 1253 EASTERN DAYLIGHT TIME, AN EMBRAER EMB-120, N256AS, OPERATED BY ATLANTIC SOUTHEAST AIRLINES (ASA) AS FLIGHT 529, CRASHED ON APPROACH TO THE WEST GEORGIA REGIONAL AIRPORT, CARROLLTON, GEORGIA. THE FLIGHTCREW WAS ATTEMPTING TO MAKE AN EMERGENCY LANDING FOLLOWING THE IN-FLIGHT SEPARATION OF A PROPELLER BLADE. THE CAPTAIN AND SEVEN PASSENGERS WERE KILLED, AND THE AIRPLANE WAS DESTROYED BY IMPACT FORCES AND A POSTCRASH FIRE. FLIGHT 529 WAS BEING CONDUCTED UNDER THE PROVISIONS OF TITLE 14 CODE OF FEDERAL REGULATIONS PART 135 AS A DOMESTIC, SCHEDULED PASSENGER SERVICE FLIGHT FROM ATLANTA, GEORGIA, TO GULFPORT, MISSISSIPPI. THE NTSB'S INVESTIGATION OF THIS ACCIDENT IS ONGOING.
Recommendation: THE NTSB RECOMMENDS THAT THE FAA: REVISE ADVISORY CIRCULAR 20-66 TO INCLUDE THE VIBRATORY TESTING OF COMPOSITE PROPELLER BLADES THAT HAVE BEEN PREVIOUSLY OPERATED FOR A SUBSTANTIAL NUMBER TO SERVICE HOURS, & COMPOSITE BLADES THAT HAVE BEEN ALTERED TO THE LIMITS SET FORTH IN FAA-APPROVED REPAIR MANUALS TO DETERMINE THE EXPTECTED EFFECTS OF AGE ON PROPELLER BLADE'S NATURAL FREQUENCIES & THE EXCITATION FREQUENCIES ASSOCIATED WITH PROPELLER OPERATION.
Original recommendation transmittal letter: PDF
Overall Status: Closed - Acceptable Action
Mode: Aviation
Location: CARROLLTON, GA, United States
Is Reiterated: No
Is Hazmat: No
Is NPRM: No
Accident #: DCA95MA054
Accident Reports: In-flight Loss of Propeller Blade Forced Landing, and Collision with Terrain Atlantic Southeast Airlines, Inc., Flight 529 Embraer EMB-120RT, N256AS
Report #: AAR-96-06
Accident Date: 8/21/1995
Issue Date: 12/20/1996
Date Closed: 2/4/2002
Addressee(s) and Addressee Status: FAA (Closed - Acceptable Action)
Keyword(s):

Safety Recommendation History
From: NTSB
To: FAA
Date: 2/4/2002
Response: The Safety Board reviewed a copy of the AC that the FAA supplied and determined that, with the issuance of the AC, the FAA has completed the work recommended. Accordingly, Safety Recommendation A-96-144 is classified "Closed--Acceptable Action."

From: FAA
To: NTSB
Date: 10/24/2001
Response: Letter Mail Controlled 10/29/2001 2:33:27 PM MC# 2010882 On September 17, 2001, the Federal Aviation Administration (FAA) issued Advisory Circular (AC) 20-66A, Vibration Evaluation of Aircraft Propellers, to include the issues outlined in this safety recommendation. The AC provides guidance and describes one method, but not the only method, for demonstrating compliance with 14 CFR 23.907 and 25.907 for the evaluation of vibration stresses on propellers installed on airplanes. I have enclosed a copy of the AC for the Board's information. I consider the FAA's action to be completed on this safety recommendation.

From: NTSB
To: FAA
Date: 5/16/2001
Response: The FAA reports that it has revised Advisory Circular (AC) 20-66, “Vibration and Fatigue Evaluation of Airplane Propellers,” to include the issues requested in this safety recommendation. The FAA published a notice of availability in the Federal Register, with the comment period ending April 2, 2001. The Board reviewed a copy of the draft AC and found that it meets the intent of the recommendation. Pending final issuance of the revised AC, Safety Recommendation A-96-144 is classified “Open--Acceptable Response.”

From: FAA
To: NTSB
Date: 3/13/2001
Response: Letter Mail Controlled 03/19/2001 2:54:01 PM MC# 2010234 The Federal Aviation Administration (FAA) has revised Advisory Circular (AC) 20-66, Vibration Evaluation of Aircraft Propellers, to include the issues outlined in this safety recommendation. The FAA has published a notice of availability in the Federal Register, with the comment period ending April 2, 2001. I have enclosed a copy of the proposed AC for the Board's information. The FAA is continuing its effort to revise 14 CFR Part 35 as indicated in previous correspondence on this safety recommendation. However, this is a long-term effort that is beyond the scope of this safety recommendation. Consequently, the FAA considers its action completed on this safety recommendation with the issuance of AC 20-66. I will provide the Board with a copy of the AC as soon as it is issued.

From: NTSB
To: FAA
Date: 8/8/2000
Response: ALTHOUGH THE FAA'S ACTIONS ADEQUATELY ADDRESS THE RECOMMENDATION, THE SAFETY BOARD IS DISAPPOINTED THAT THE FAA'S FINAL ACTION IS NOW NOT SCHEDULED TO OCCUR FOR MORE THAN 5 YEARS AFTER THE BOARD ISSUED THIS RECOMMENDATION. THE FAA HAS ANTICIPATED PUBLISHING AN NPRM AND NOTICE OF REVISIONS TO AC 20-66 IN THE FEDERAL REGISTER SINCE 1998; THE BOARD SINCERELY HOPES THE SCHEDULE FOR DECEMBER 2001 WILL BE MET. PENDING ISSUANCE OF THE REVISION TO AC 20-66, A-96-144 IS CLASSIFIED "OPEN--UNACCEPTABLE RESPONSE."

From: FAA
To: NTSB
Date: 6/1/2000
Response: Letter Mail Controlled 06/06/2000 12:35:19 PM MC# 2000714 THE FAA IS CONTINUING ITS EFFORTS TO REVISE ADVISORY CIRCULAR (AC) 20-66, VIBRATION EVALUATION OF AIRCRAFT PROPELLERS, TO INCLUDE THE ISSUES OUTLINED IN THIS RECOMMENDATION. IN DEVELOPING THE REVISION TO AC 20-66, THE FAA DETERMINED THAT REGULATORY CHANGES ALSO NEED TO BE MADE TO ADDRESS THE PROPELLER VIBRATION REQUIREMENTS (14 CFR PART 35) BEFORE THE AC CAN BE REVISED. CONSEQUENTLY, THE FAA TASKED THE AVIATION RULEMAKING ADVISORY COMMITTEE (ARAC) TO PROPOSE APPROPRIATE CHANGES TO 14 CFR PART 35 AND AC 20-66. THE ARAC HAS COMPLETED THIS TASK AND IN MARCH 2000, PROVIDED ITS RECOMMENDATIONS FOR THESE 2 CHANGES TO THE FAA FOR REVIEW. THE FAA HAD ANTICIPATED PUBLISHING A NOTICE IN THE FEDERAL REGISTER ANNOUNCING THE REVISION TO THE AC IN JANUARY 1999. HOWEVER, THIS EFFORT IS TAKING LONGER THAN ORIGINALLY ANTICIPATED SINCE IT WAS DETERMINED THAT REGULATORY CHANGES NEED TO BE MADE ALONG WITH THE AC. THE FAA ANTICIPATES PUBLISHING A NOTICE OF PROPOSED RULEMAKING PROPOSING TO REVISE 14 CFR PART 35 AND A NOTICE ANNOUNCING THE REVISION TO AC 20-66 IN THE FEDERAL REGISTER BY DECEMBER 2001. I WILL KEEP THE BOARD INFORMED OF THE FAA'S PROGRESS ON THIS RECOMMENDATION.

From: NTSB
To: FAA
Date: 11/10/1998
Response: A-96-144 ASKED THE FAA TO REVISE ADVISORY CIRCULAR (AC) 20-66 TO INCLUDE THE VIBRATORY TESTING OF COMPOSITE PROPELLER BLADES THAT HAVE BEEN PREVIOUSLY OPERATED FOR A SUBSTANTIAL NUMBER OF SERVICE HOURS & COMPOSITE BLADES THAT HAVE BEEN ALTERED TO THE LIMITS SET FORTH IN FAA-APPROVED REPAIR MANUALS TO DETERMINE THE EXPECTED EFFECTS OF AGE ON PROPELLER VIBRATION & PROVIDE GUIDELINES FOR RPM MARGIN BETWEEN A PROPELLER BLADE'S NATURAL FREQUENCIES & THE EXCITATION FREQUENCIES ASSOCIATED WITH PROPELLER OPERATION PENDING OUR REVIEW OF THE REVISION TO AC 20-66, A-96-144 IS CLASSIFIED "OPEN--ACCEPTABLE RESPONSE."

From: FAA
To: NTSB
Date: 9/15/1998
Response: (Letter Mail Controlled 9/18/98 2:40:19 PM MC# 981158) THE FAA IS REVISING ADVISORY CIRCULAR (AC) 20-66, VIBRATION EVALUATION OF AIRCRAFT PROPELLERS, TO INCLUDE THE ISSUES OUTLINED IN THIS RECOMMENDATION. THE FAA ANTICIPATES PUBLISHING A NOTICE IN THE FEDERAL REGISTER ANNOUNCING THE REVISION TO THE AC IN JANUARY 1999.

From: FAA
To: NTSB
Date: 8/14/1997
Response: The FAA is working with technical experts to include the items outlined in this safety recommendation in a revision to Advisory Circular (AC) 20-66. The FAA will publish a notice in the Federal Register announcing the revision to the AC. I will keep the Board apprised of the FAA's progress on this safety recommendation.

From: NTSB
To: FAA
Date: 5/1/1997
Response: THE FAA STATED IT HAD MET WITH REPRESENTATIVES OF HAMILTON STANDARD FROM FEBRUARY 3 THROUGH FEBRUARY 14, 1997, TO DISCUSS THE BOARD'S RECOMMENDATIONS, TO SUMMARIZED THOSE ACTIONS THAT MAY HAVE ALREADY BEEN ACCOMPLISHED, TO EVALUATE THOSE ACTIONS THAT NEED FURTHER EVALUATION, & TO DEVELOP AN ACTION PLAN TO OUTLINE THE ACTIONS THAT NEED TO BE TAKEN TO ADDRESS THESE RECOMMENDATIONS. THE FAA ANTICIPATES THAT THE ACTION PLAN WILL BE COMPLETED BY MAY 1997. BASED ON THIS INFO, THE BOARD CLASSIFIES A-96-142, -144, -145, & -146 "OPEN--ACCEPTABLE RESPONSE."

From: FAA
To: NTSB
Date: 3/3/1997
Response: THE FAA AGREES WITH THIS RECOMMENDATION & IS WORKING WITH HAMILTON STANDARD TO DEVELOP AN ACTION PLANT TO ADDRESS THIS SAFETY ISSUE. THE FAA MET WITH HAMILTON STANDARD ON FEBRUARY 3 THROUGH 14, 1997, TO DISCUSS THIS RECOMMENDATION, SUMMARIZE ACTIONS THAT MY HAVE ALREADY BEEN ACCOMPLISHED, EVALUATE ACTIONS THAT NEED FURTHER ACTION, & TO DEVELOP AN ACTION PLAN OUTLINE THE ACTIONS THAT NEED TO BE TAKEN TO ADDRESS THIS RECOMMENDATION. THE FAA ANTICIPATES THE ACTION PLAN WILL COMPLETED BY MAY 1997.