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Safety Recommendation Details

Safety Recommendation A-92-026
Details
Synopsis: ON APRIL 5, 1991, ATLANTIC SOUTHEAST AIRLINES, INC., FLIGHT 2311, AN EMBRAER EMB-120, N270AS. CRASHED DURING A LANDING APPROACH TO RUNWAY 07 AT THE GLYNCO JETPORT, BRUNSWICK, GEORGIA. THE FLIGHT WAS SCHEDULED COMMUTER FLIGHT FROM ATLANTA TO BRUNSWICK, GEORGIA, OPERATING UNDER THE PROVISIONS OF TITLE 14 CODE OF FEDERAL REGULATIONS (CFR) PART 135, AND WAS BEING CONDUCTED UNDER INSTRUMENT FLIGHT RULES. THE AIRPLANE WAS OPERATING VISUAL METEOROLOGICAL CONDITIONS AT THE TIME OF THE ACCIDENT. THE AIRPLANE WAS DESTROYED; AND THE TWO PILOTS, THE FLIGHT ATTENDANT, AND ALL 20 PASSENGERS RECEIVED FATAL INJURIES.
Recommendation: THE NTSB RECOMMENDS THAT THE FEDERAL AVIATION ADMINISTRATION: EXAMINE THE CERTIFICATION BASIS OF OTHER MODEL PROPELLER SYSTEMS THAT HAVE SAME DESIGN CHARACTERISTICS AS THE HAMILTON STANDARD PROPELLER MODEL 14RF AND ENSURE THAT THE FAIL-SAFE FEATURES OF THOSE PROPELLER SYSTEMS WILL FUNCTION PROPERLY IN THE EVENT OF UNFORESEEN WEAR OF COMPONENTS IN THE PROPELLER SYSTEM.
Original recommendation transmittal letter: PDF
Overall Status: Closed - Acceptable Action
Mode: Aviation
Location: BRUNSWICK, GA, United States
Is Reiterated: No
Is Hazmat: No
Is NPRM: No
Accident #: DCA91MA033
Accident Reports: Atlantic Southeast Airlines, Inc. Flight 2311 Uncontrolled Collision with Terrain an Embraer EMB-120, N270AS
Report #: AAR-92-03
Accident Date: 4/5/1991
Issue Date: 5/14/1992
Date Closed: 4/16/1996
Addressee(s) and Addressee Status: FAA (Closed - Acceptable Action)
Keyword(s):

Safety Recommendation History
From: NTSB
To: FAA
Date: 4/16/1996
Response: FOLLOWUP FOR BOTH LETTERS 10/26/95 & 1/17/96) THE BOARD NOTES THAT THE FAA & HAMILTON STANDARD HAVE CONDUCTED EXTENSIVE EVALUATIONS, TESTS, & ANALYSES OF THE HAMILTON STANDARD PROPELLER MODEL 14RF & PROPELLER OF SIMILAR DESIGN. AS A RESULT OF THIS WORK, A BALLSCREW QUILL DAMPER & SECONDARY DRIVE QUILL HAVE BEEN DEVELOPED TO PREVENT THE LOSS OF CONTROL OF A PROPELLER. THE BOARD BELIEVES THAT THE INSTALLATION OF THESE COMPONENTS SHOULD BRING THE PROPELLER SYSTEMS INTO COMPLIANCE WITH 14 CFR PART 35. HOWEVER, THE BOARD BELIEVES THAT THE REPETITIVE INSPECTION INTERVALS OF THE COMPONENTS OF THE PROPELLER CONTROL UNIT SHOULD NOT HAVE BEEN INCREASED UNTIL THE SECONDARY DRIVE QUILL IS INSTALLED. WHILE THE INSTALLATION OF THE SERVO BALLSCREW QUILL DAMPER APPEARS TO GREATLY REDUCE THE WEAR OF THE SERVO BALLSCREW INTERNAL SPLINE TEETH, THE BOARD REMAINS CONCERNED ABOUT POTENTIAL FAILURES OF OTHER CRITICAL COMPONENTS WITHIN THE PCU. AS FOUND IN THE 1991 BRUNSWICK, GEORGE, ACCIDENT THAT PRECIPITATED THESE RECOMMENDATIONS, A FAILURE WITHIN THE PCU CAN RESULT IN AN UNCONTROLLABLE PROPELLER & SUBSEQUENT SUDDEN LOSS OF CONTROL OF THE AIRPLANE. BECAUSE OF THE CRITICAL NATURE OF THE PCU COMPONENTS, THE BOARD BELIEVES THAT IT WOULD HAVE BEEN PRUDENT TO MAINTAIN THE 1,500-HOUR REPETITIVE INSPECTION REQUIREMENT FOR THE PCU UNTIL SUFFICIENT SERVICE EXPERIENCE WAS GAINED. DESPITE ITS CONCERNS ABOUT THE DURATION BETWEEN INSPECTIONS, THE BOARD FINDS THAT THE ACTIONS TAKEN BY THE FAA COMPLY WITH THE INTENT OF THESE THEREFORE A-92-25 & -26 ARE CLASSIFIED "CLOSED--ACCEPTABLE ACTION."

From: FAA
To: NTSB
Date: 1/17/1996
Response: THE FAA ISSUED AIRWORTHINESS DIRECTIVE 95-22-12 APPLICABLE TO HAMILTON STANDARD 14RF, 247F, 14SF, & 6/5500/F SERIES PROPELLERS. THIS AD INCREASES THE REPETITIVE INSPECTION PROPELLER CONTROL UNIT SERVO BALLSCREW INTERNAL SPLINE TEETH INSPECTION INTERVAL FROM 1,500 HOURS TIME-IN-SERVICE TO 2,500 HOURS TIME-IN-SERVICE FOR PROPELLERS THAT HAVE A BALLSCREW QUILL DAMPER INSTALLED. IN ADDITION, THE FAA REEVALUATED THE OPTIONAL INSTALLATION OF THE SECONDARY DRIVE QUILL & HAS ADDED A NEW COMPLIANCE END DATE OF 6/30/98, FOR INSTALLATION OF THE SECONDARY DRIVE QUILL. THIS AD ALSO REQUIRES AN INITIAL TORQUE CHECK INSPECTION OF THE PRIMARY BALLSCREW QUILL ONCE THE SECONDARY DRIVE QUILL IS INSTALLED. I HAVE ENCLOSED A COPY OF THE AD FOR THE BOARD'S INFO. I CONSIDER THE FAA'S ACTION TO BE COMPLETED ON THESE RECOMMENDATIONS.

From: FAA
To: NTSB
Date: 10/26/1995
Response: THE FAA AGREES WITH THE ABOVE RECOMMENDATIONS & HAS TAKEN EXTENSIVE ACTIONS TO ADDRESS THESE ISSUES. IN JUNE 1992, THE FAA'S HAMILTON STANDARD CERTIFICATION REVIEW TEAM COMPLETED ITS CERTIFICATION REVIEW OF THE HAMILTON STANDARD 14RF PROPELLER SYSTEM & OTHER MODEL PROPELLER SYSTEMS THAT HAVE THE SAME DESIGN CHARACTERISTICS AS THE HAMILTON STANDARD 14RF. THE FAA REVIEWED THE VIBRATION SPECTRUM THAT WOULD BE ENCOUNTERED IN FLIGHT ON THOSE AIRCRAFT FOR WHICH THE PROPELLERS ARE CERTIFICATED. THE REVIEW ALSO INCLUDED AN EXAMINATION OF THE DESIGN & CERTIFICATION PROCESS USED TO APPROVE THE HAMILTON STANDARD 14RF, 14SF, & 6/5500/F-1 MODEL PROPELLERS. THE TEAM CONCLUDED THAT EACH OF THE PROPELLER MODELS WAS IN COMPLIANCE WITH 14 CFR PART 35 & HAD BEEN CERTIFICATED CORRECTLY. BASED ON THE INFO THAT THE CERTIFICATION REVIEW TEAM COMPLIED, FOUR RECOMMENDATIONS WERE DEVELOPED. THE FOLLOWING IS A STATUS OF FAA ACTIONS ACCOMPLISHED TO DATE TO ADDRESS THESE RECOMMENDATIONS. THE FAA ACTIONS ENCOMPASS ALL SAFETY CONCERNS OUTLINED A-92-25 THROUGH -27. 1. REVISE AIRWORTHINESS DIRECTIVE 92-08-03, DATED 4/27/92, WHICH REQUIRES A 900-HOUR REPETITIVE INSEPECTION OF THE SERVO BALLSCREW INTERNAL SPLINE TO EXTEND ITS APPLICABILITY TO INCLUDE ALL MODELS OF THE HAMILTON STANDARD 14RF, 14SF, & 6/5500/F SERIES PROPELLERS.

From: NTSB
To: FAA
Date: 10/6/1992
Response: THE BOARD NOTES THAT THE FAA'S SPECIAL CERTIFICATION REVIEW TEAM EXAMINED THE DESIGN & CERTIFICATION PROCESS USED TO APPROVE THE HAMILTON STANDARD 14RF SERIES PROPELLERS & AS A RESULT OF THAT REVIEW, THE FAA PLANS TO REVISE TWO AIRWORTHINESS DIRECTIVES (AD), ISSUE A NEW AD, & ADVISE HAMILTON STANDARD TO INCORPORATE A FAIL-SAFE FEATURE INTO THE DESIGN OF 14RF, 14SF, & 6/5500/F-1 MODEL PROPELLERS. PENDING FURTHER INFORMATION, RECOMMENDATIONS A-92-25 THROUGH -27 ARE CLASSIFIED AS "OPEN--ACCEPTABLE RESPONSE."

From: FAA
To: NTSB
Date: 7/22/1992
Response: THE FAA SPECIAL CERTIFICATION REVIEW TEAM EXAMINED THE DESIGN AND CERTIFICATION PROCESS USED TO APPROVE THE HAMILTON STANDARD 14RF SERIES PROPELLERS. THE TEAM ALSO EXAMINED THE HAMILTON STANDARD 14SF AND 6/5500/F SERIES PROPELLERS. AS A RESULT OF THIS REVIEW, THE FAA WILL TAKE THE FOLLOWING ACTIONS TO ADDRESS THESE RECOMMENDATIONS: REVISE AIRWORTHINESS DIRECTIVE (AD) 92-08-03, WHICH REQUIRES A 900 HOUR REPETITIVE INSPECTION OF THE SERVO BALLSCREW INTERNAL SPLINE, TO EXTEND ITS APPLICABILITY TO INCLUDE ALL MODELS OF THE 14RF, 14SF, AND 6/5500/F MODEL PROPELLERS. ISSUE AN AD TO MANDATE PROPELLER DISASSEMBLY AND INSPECTION OF ALL CRITICAL ITEMS. REVISE AD T91-11-51 TO HAVE ALL TITANIUM-NITRATED OIL TRANSFER TUBES REMOVED FROM SERVICE AND NO LONGER ALLOWED TO BE USED. ADDITIONALLY, THE FAA WILL REVIEW ALL DESIGN CHANGES TO CRITICAL COMPONENTS SINCE JANUARY 1987. ADVISE HAMILTON STANDARD TO INCORPORATE A FAIL-SAFE FEATURE INTO THE DESIGN OF 14RF, 14SF, AND 6/5500/F-1 MODEL PROPELLERS. THE FAIL-SAFE DESIGN FEATURE WILL BE CERTIFICATED WITHIN 2 YEARS WITH INCORPORATION IN ALL IN-SERVICE PROPELLER UNITS WITHIN 3 YEARS THEREAFTER.