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Safety Recommendation Details

Safety Recommendation A-96-145
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: REQUIRE THAT HAMILTON STANDARD CONSIDER LONG-TERM, ATMOSPHERIC-INDUCED CORROSION EFFECTS & AMEND THE COMPONENT MAINTENANCE MANUAL (CMM) INSPECTION PROCEDURE TO REFLECT AN APPROPRIATE INTERVAL THAT WILL DETECT CORROSION WITHIN THE TAPER BORE.
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: 10/27/1999
Addressee(s) and Addressee Status: FAA (Closed - Acceptable Action)
Keyword(s):

Safety Recommendation History
From: NTSB
To: FAA
Date: 10/27/1999
Response: THE SAFETY BOARD IS PLEASED THAT THE FAA HAS COMPLETED THE ABOVE ACTIONS IN RESPONSE TO A-96-145. HOWEVER, WE NOTE THAT ALTHOUGH THE FAA RESPONSE STATES THAT "DETAILED PROCEDURES FOR INSPECTION AND REPAIR OF MECHANICAL AND CORROSION DAMAGE" HAVE BEEN DEVELOPED, IT DOES NOT ADDRESS WHETHER OR NOT THE CMM INSPECTION PROCEDURES "REFLECT AN APPROPRIATE INTERVAL THAT WILL DETECT ANY CORROSION WITHIN THE TAPER BORE," AS RECOMMENDED. THEREFORE, SAFETY BOARD STAFF CONTACTED HAMILTON STANDARD. HAMILTON STANDARD STATED THAT THE REVISION TO THE CMM PLACES A REQUIREMENT FOR AN INSPECTION OF THE PROPELLER BLADE SHANK AND TAPER BORE FOR DAMAGE, INCLUDING CORROSION, IN THE "MAJOR INSPECTION" SECTION OF THE MANUAL. MAJOR INSPECTION INTERVALS ARE 9,000 HOURS FOR THE 14RF-9 AND RANGE FROM 6,000 HOURS TO 10,500 HOURS FOR THE OTHER PROPELLER SYSTEMS. A MAJOR INSPECTION REQUIREMENT AND THE APPLICABLE INTERVAL ARE PROVIDED IN THE "AIRWORTHINESS LIMITATIONS" SECTION OF EACH MANUAL. THE INSPECTION PROCEDURE IS PROVIDED IN THE "DEDICATED REPAIR" SECTION OF THE MANUAL. THE INSPECTION CAN IDENTIFY UNACCEPTABLE SURFACE DAMAGE, INCLUDING THAT CAUSED BY LONG-TERM ATMOSPHERIC INDUCED CORROSION EFFECTS. ALL EXPOSED METAL SURFACES OF THE ALUMINUM BLADE SPAR, INCLUDING WITHIN THE TAPER BORE, ARE ADDRESSED. HAMILTON STANDARD REPORTED THAT THE INSPECTION PROCESS HAS BEEN DEMONSTRATED TO THE SATISFACTION OF FAA REPRESENTATIVES. BLADES WITH TAPER BORE CORROSION WILL BE REPAIRED IN ACCORDANCE WITH PREVIOUSLY APPROVED TAPER BORE REPAIRS IF THE DAMAGE IS WITHIN REPAIR LIMITS OR THEY WILL BE REMOVED FROM SERVICE. BECAUSE HAMILTON STANDARDS' REVISIONS TO ITS CMM MEET THE INTENT OF A-96-145, IT IS CLASSIFIED "CLOSED--ACCEPTABLE ACTION."

From: FAA
To: NTSB
Date: 5/17/1999
Response: Letter Mail Controlled 5/19/99 4:18:21 PM MC# 990536 ON 10/28/98, HAMILTON STANDARD FORWARDED TO THE FAA THE FIRST COMPONENT MAINTENANCE MANUAL FOR MODEL 14RF WITH DETAILED PROCEDURES FOR INSPECTION AND REPAIR OF MECHANICAL AND CORROSION DAMAGE. THE FAA APPROVED THE INSPECTION PROCEDURES ON 1/8/99, AND ESTABLISHED A SCHEDULE TO PREPARE PROCEDURES, TRAIN INSPECTORS AND REPAIR FACILITY PERSONNEL, VALIDATE REPAIR PROCESSES AND ACTIONS, AND COMPLETE SEVEN COMPONENT MAINTENANCE MANUALS FOR ALL 14RF, 14SF, AND 6/5500/F MODELS. ALL MILESTONES IN THE SCHEDULE WERE COMPLETED ON 4/23/99. I BELIEVE THAT THE FAA HAS ADDRESSED THE FULL INTENT OF THIS RECOMMENDATION, AND I CONSIDER THE FAA'S ACTION TO BE COMPLETED.

From: NTSB
To: FAA
Date: 11/10/1998
Response: A-96-145 ASKED THE FAA TO REQUIRE THAT HAMILTON STANDARD CONSIDER LONG-TERM ATMOSPHERIC-INDUCED CORROSION EFFECTS & AMEND THE COMPONENT MAINTENANCE MANUAL (CMM) INSPECTION PROCEDURE TO REFLECT AN APPROPRIATE INTERVAL THAT WILL DETECT ANY CORROSION WITHIN THE PROPELLER BLADES TAPER BORE. PENDING FAA APPROVAL OF THE HAMILTON STANDARD PROGRAM & OUR REVIEW OF THE PROPOSED REVISION TO THE PROPELLER CMM, A-96-145 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) HAMILTON STANDARD HAS DEVELOPED A PROGRAM TO ESTABLISH & IMPLEMENT AN INSPECTION FOR THE PRESENCE OF CORROSION IN THE BLADE TAPER BORE. THE PROGRAM COVERS DEVELOPMENT OF INSPECTION TECHNIQUES INTENDED TO DETECT CORROSION, A RECURRING INSPECTION INTERVAL IN FLIGHT HOURS &/OR CALENDAR TIME, ESTABLISHMENT OF PROBABILITY OF DETECTION FOR INSPECTION METHODS, & PROCEDURES FOR REPAIR OF EXISTING DAMAGE. THE THE FAA IS CURRENTLY REVIEWING THIS PROGRAM FOR APPROVAL. ONCE THE PROGRM IS APPROVED, THE INSPECTION & REPAIR PROCEDURES WILL BE INCLUDED IN THE PROPELLER COMPONENT MAINTENANCE MANUAL.

From: FAA
To: NTSB
Date: 8/14/1997
Response: Hamilton Standard is developing a program to establish and implement an inspection for the presence of corrosion in the blade taper bore. Hamilton Standard anticipates submitting the plan to the FAA for approval in December 1997. The program covers development of inspection techniques intended to detect corrosion, a recurring inspection interval in flight hours and/or calendar time, establishment of probability of detection for inspection methods, and procedures for repair of existing damage. The program also provides for the submission of the proposed inspection and repair procedures and recommended intervals to the FAA for approval for incorporation in the Propeller Component Maintenance Manual, which is the Federal Aviation Regulations recognized instructions for continued airworthiness.

From: NTSB
To: FAA
Date: 5/1/1997
Response: THE FAA STATE IT HAD MET WITH REPRESENTATIVES OF HAMILTON STANDARD FROM FEBRUARY 3 THROUGH FEBRUARY 14, 1997, TO DISCUSS THE BOARD'S RECOMMENDATIONS, TO SUMMARIZE 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 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 & IN WORKING WITH HAMILTON STANDARD TO DEVELOP AN ACTION PLAN TO ADDRESS THIS SAFETY ISSUE. THE FAA MET WITH HAMILTON STANDARD ON FEBRUARY 3 THROUGH 14, 1997, TO DISCUSS THIS RECOMMENDATION, SUMMARIZE ACTIONS THAT MAY 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 BE COMPLETED BY MAY 1997.