Skip Ribbon Commands
Skip to main content
Safety Recommendation Details

Safety Recommendation A-76-064
Details
Synopsis: ON MARCH 11, 1976, THE NATIONAL TRANSPORTATION SAFETY BOARD COMPLETED ITS PUBLIC HEARING INTO THE OVERSEAS NATIONAL AIRWAYS, INC., ACCIDENT OF NOVEMBER 12, 1975. DURING THAT ACCIDENT, THE CREW OF A MCDONNELL DOUGLAS DC-10-30F REJECTED TAKEOFF FROM JOHN F. KENNEDY INTERNATIONAL AIRPORT AFTER A NUMBER OF LARGE BIRDS WERE INGESTED INTO THE NO. 3 ENGINE. ONE OF THE BASIC ISSUES IN THE ACCIDENT WAS THE CATASTROPHIC DISINTEGRATION OF THE ENGINE.
Recommendation: AMEND 14 CFR 33.77 TO INCREASE THE MAXIMUM NUMBER OF BIRDS IN THE VARIOUS SIZE CATEGORIES REQUIRED TO BE INGESTED INTO TURBINE ENGINES WITH LARGE INLETS. THESE INCREASED NUMBERS AND SIZES SHOULD BE CONSISTENT WITH THE BIRDS INGESTED DURING SERVICE EXPERIENCE OF THESE ENGINES.
Original recommendation transmittal letter: PDF
Overall Status: Closed - Acceptable Action
Mode: Aviation
Location: Jamaica, NY, United States
Is Reiterated: No
Is Hazmat: No
Is NPRM: No
Accident #: DCA76AZ010
Accident Reports: Overseas National Airways, Inc., Douglas DC-10-30, N1032F
Report #: AAR-76-19
Accident Date: 11/12/1975
Issue Date: 4/1/1976
Date Closed: 7/30/1986
Addressee(s) and Addressee Status: FAA (Closed - Acceptable Action)
Keyword(s): Wildlife

Safety Recommendation History
From: NTSB
To: FAA
Date: 9/18/2006
Response: Notation 5760A: The National Transportation Safety Board has reviewed the Federal Aviation Administration’s (FAA) Notice of Proposed Rulemaking (NPRM), titled “Airworthiness Standards; Engine Bird Ingestion,” which was published in 71 Federal Register 41184 on July 20, 2006. The notice proposes amending the aircraft turbine engine type certification standards to reflect recent analysis of the threat flocking birds present to turbine-engine aircraft. The Safety Board generally supports the NPRM but has concerns about certain elements of the proposed rule, which are discussed below. Large Flocking Bird Ingestion Standard The Safety Board has investigated a number of bird ingestion-related events, including a rejected takeoff accident involving a DC-10-30F, operated by Overseas National Airways, Inc., that occurred at John F. Kennedy International Airport on November 12, 1975. The accident was caused by the ingestion of several large birds into the No. 3 engine. As a result of the investigation, the Board determined that the bird ingestion certification provision in effect at that time did not provide adequate safeguards against the ingestion potential of future large turbofan engines; therefore, the Safety Board issued Safety Recommendation A-76-64 to the FAA, recommending the following: Amend 14 CFR [Code of Federal Regulations] 33.77 to increase the maximum number of birds in the various size categories required to be ingested into turbine engines with large inlets. These increased numbers and sizes should be consistent with the birds ingested during service experience of these engines. Subsequently, the FAA performed a study of bird ingestions that focused on the time period from 1981 to 1983 and issued a report titled A Study of Bird Ingestions Into Large High Bypass Ratio Turbine Aircraft Engines. The study concluded that additional bird ingestion service data was needed to improve the validity of the FAA’s database of bird ingestion events. The Safety Board was satisfied with the FAA’s work at the time and concurred with the FAA’s determination that additional data gathering was needed to make improvements. On July 30, 1986, the Safety Board classified Safety Recommendation A-76-64 “Closed–Acceptable Action.” The Board notes that in 2001, the FAA commissioned a study to further collect and analyze data and the results of that study were reported in Report No. DOT/FAA/ARTN03/60, Study of Bird Ingestions into Aircraft Turbine Engines (1968 to 1999). The report summarized the historical bird threat and resulting impact to flight safety based on 30 years of bird ingestion data. The subject NPRM indicates that the working groups responsible for developing the proposed 14 CFR Part 33 requirements contained in the NPRM used this report to support their efforts. The Safety Board supports the inclusion of the requirement concerning large flocking birds in the bird ingestion airworthiness standard for aircraft engines as outlined in this NPRM. However, the Safety Board is concerned that the FAA has elected to use a snow goose with a weight of about 8 pounds (3.65 kilograms) as representative of a large flocking bird. The Board notes that the Canada goose, which is far more prevalent than the snow goose, is found in the 48 contiguous states and Alaska and is significantly larger than the snow goose, weighing up to 24 pounds. The ingestion of Canada geese is not uncommon. The Safety Board investigated an uncontained fan blade separation that occurred on an American Airlines Fokker F100 airplane equipped with Rolls-Royce Tay engines after three Canada geese were ingested by the right engine during takeoff at LaGuardia Airport, New York, New York, on September 4, 2003. In addition to the three geese that were ingested by the right engine, birds struck the airplane at four other locations on the nose and left wing. The Board is also aware of a U.S. Air Force E3A AWACS airplane equipped with Pratt & Whitney TF33-P-100A engines that crashed at Elmendorf Air Force Base, Alaska, after two engines on one side of the airplane lost power following the ingestion of Canada geese. The Safety Board is also concerned about the FAA’s proposal to conduct the flocking bird ingestion test at only 90 percent of an engine’s rated thrust. The Board concurs with the FAA’s assessment that the world’s jetliner fleet uses de-rated power for most takeoffs. However, the Board also notes that all other engine certification tests specified in Part 33 are conducted at maximum power. The level of engine unbalance that occurs if a blade breaks off after a birdstrike increases exponentially with the rotor’s speed. Thus, the level of engine unbalance from a fractured fan blade would be significantly higher if the engine were operating at maximum rpm than if the engine were operating at 90 percent power. Although the Safety Board recognizes that conducting the flocking bird ingestion test with a Canada goose and with the engine operating at maximum rpm would require a more robust design, the Board believes that this robust design would be more likely to survive a bird ingestion event. Risk Assessment The FAA’s study, Study of Bird Ingestions into Aircraft Turbine Engines (1968 to 1999), cites only one catastrophic aircraft consequence involving birds, and the FAA based its risk factors on that single event. The Board is aware of two other events that were nearly accidents that the FAA should consider in its risk assessment. In one, a Boeing 757 taking off from Orange County’s John Wayne Airport, California, ingested birds in both engines after the airplane was past rotation speed (Vr) speed, and the nose wheel was off the ground. One engine was destroyed and lost all power immediately and the other engine was badly damaged. The captain sensed that the airplane would not be able to continue safe flight and rejected the takeoff. Postevent analysis indicated that, if the captain had continued the takeoff, the damaged engine would not have produced power for a period long enough for the airplane to return to the airport. In the other event, a Douglas DC-9 airplane was on short final for landing at Kansas City International Airport, Kansas City, Missouri, when the engines ingested Canada geese, causing both engines to lose power. The airplane was able to land safely because of its proximity to the runway. If the 757 pilot had not made an instantaneous decision to reject the takeoff even though he was past Vr or if the DC-9 had been further out on the approach, it is likely that both airplanes would have crashed following the bird ingestions. Because the FAA’s risk assessment did not consider these events, the Board believes that the NPRM’s risk factors do not adequately represent the potential risks associated with bird ingestions. Preexisting Damage In 1991, the Safety Board participated in the investigation of a rejected takeoff at Shannon Airport, Shannon, Ireland, involving a Delta Air Lines Boeing 767-332ER that experienced a fan blade fracture in the No. 2 engine following a bird ingestion. Inspection of the fractured fan blade revealed a preexisting nick on the leading edge of the blade at the base of the location where the bird impacted the blade. Based on these findings, it was believed that the impact force of the ingested bird caused the fan blade to twist and bend, resulting in the fan blade tearing at the location of the preexisting nick. All of the remaining fan blades were badly gouged and the inside of the inlet cowl surface was extensively torn. Based on this event, the Safety Board was concerned that the then-current engine foreign object ingestion certification requirements, including the bird ingestion requirements, did not take into account blade imperfections that are normally found in service. Consequently, the Safety Board issued Safety Recommendation A-92-49, which asked the FAA to do the following: Modify the certification requirements for turbine engines (14 CFR section 33.77) to require that foreign object ingestion requirements consider the adverse effects of preexisting service-acceptable blade damage, such as nicks, scrapes, and gouges, that can occur during normal operation and that may be present during revenue service. To address this recommendation, the FAA amended the type certification standards for aircraft turbine engines with regard to bird ingestion by imposing more stringent criteria in terms of size and number of birds. The FAA then issued Advisory Circular 33.76-1 to provide guidance and methods for demonstrating compliance with the new bird ingestion standards. Although the Safety Board welcomed the improved certification standards, the new regulations failed to address the effects of preexisting or service-acceptable damage in the new certification standards. Therefore, on January 29, 2001, the Safety Board classified Safety Recommendation A-92-49 “Closed—Unacceptable Action.” The Safety Board notes that the certification standards proposed in the NPRM still do not address preexisting or service-acceptable damage. Taking this damage into consideration is a vital component of a comprehensive bird ingestion standard. Therefore, the Safety Board encourages the FAA to include the effects of preexisting damage during bird ingestion certification to ensure there is sufficient margin against preexisting damage effects. In conclusion, the Safety Board concurs with the FAA’s intent for the proposed changes to the engine bird ingestion standards but believes that the proposed standards do not go far enough to ensure safe flight in the event of a bird ingestion event. The Board hopes that the FAA will reassess the flocking bird ingestion test criteria to make the test more representative of a worst-case scenario—given the size of the bird and the service-acceptable blade damage—that would result in in-service engines that could withstand a realistic bird ingestion. Further, the Board hopes that the FAA will continue to monitor changes in bird patterns within airport environments and incorporate preexisting damage effects into the certification standards. Thank you for the opportunity to provide comments on this NPRM.

From: NTSB
To: FAA
Date: 7/30/1986
Response: The cf6-50a high bypass-ratio turbofan engine, the subject of this recommendation, was certificated based on bird ingestion testing of six 1-1/4 pound birds. We note that amendment 6 to 14 cfr, part 33, which became effective october 31, 1974, requires these large engines to be tested with eight 1-1/2 pound birds. We were pleased to receive your report a study of bird ingestion into high bypass ratio turbine aircraft engines and thank you for your assurance that the new engines are significantly improved in their ability to safely ingest the size and number of birds encountered in actualservice operations. Safety recommendation a-76-64 is now classified as closed--acceptable action.

From: FAA
To: NTSB
Date: 5/9/1986
Response: "...THE ENGINE INVOLVED IN THE SUBJECT ACCIDENT, THE CF6-50A HIGH BYPASS-RATIO TURBOFAN ENGINE WAS CERTIFIED BASED UPON BIRD INGESTION TESTING WITH SIX 1-1/4 POUND BIRDS. AMENDMENT 6 TO 14 CFR PART 33, WHICH BECAME EFFECTIVE OCTOBER 31, 1974, REQUIRES LARGE ENGINES TO BE TESTED WITH EIGHT 1-1/2 POUND BIRDS; HOWEVER, NO LARGE ENGINES HAD BEEN CERTIFIED UNDER THESE STANDARDS WHEN RECOMMENDATION A-76-64 WAS ISSUED. SINCE LATE 1977, LARGE TURBOFAN ENGINES HAVE MET AMENDMENT 6 OR LATER BIRD INGESTION REQUIREMENTS, AND A RECENT BIRD INGESTION STUDY HAS SHOWN THAT THESE ENGINES ARE SIGNIFICANTLY IMPROVED IN THEIR ABILITY TO SAFELY INGEST THE SIZE AND NUMBER OF BIRDS ENCOUNTERED IN ACTUAL SERVICE OPERATION. THEREFORE, I BELIEVE THE FEDERAL AVIATION ADMINISTRATION (FAA) HAS, IN FACT, COMPLIED WITH THE INTENT AND SPIRIT OF SAFETY RECOMMENDATION A-76-64."

From: NTSB
To: FAA
Date: 12/10/1985
Response: We are pleased to learn of the FAA's studies regarding the tolerance of the newer class of engines to bird ingestion, and the weight and/or number of birds required to be ingested during engine certification testing. We thank you for your offer to keep the safety board advised of progress. This recommendation remains classified in an open--acceptable action status.

From: FAA
To: NTSB
Date: 10/29/1985
Response: THE FAA HAS DECIDED TO GATHER ADDITIONAL BIRD INGESTION SERVICE DATA TO IMPROVE OUR STATISTICAL DATA BASE ON THE LATEST CLASS OF ENGINES (I.E., THOSE CERIFICATED TO THE CURRENT REGULATIONS AND METHODS). THE STUDY ADDRESSED ABOVE CONTAINS ONLY A RELATIVELY SMALL AMOUNT OF DATA ON THE LATEST CLASS OF ENGINES BECAUSE THEY WERE ONLY BEGINNING TO ENTER SERVICE AT THE TIME THE DATA WAS BEING GATHERED. THERE DOES EXIST, HOWEVER, SUFFICIENT DATA ON THESE ENGINES TO CONCLUDE THAT THEY REPRESENT A SIGNIFICANT IMPROVEMENT OVER PREVIOUS ENGINES IN THEIR TOLERANCE TO BIRD INGESTION. THE ADDITIONAL DATA GATHERING MENTIONED ABOVE WILL ALLOW THE FAA TO QUANTIFY THIS IMPROVEMENT. DETAILS OF THESE FUTURE STUDIES ARE BEING DEVELOPED. I WILL KEEP THE BOARD ADVISED OF PROGRESS AND ACTIONS.

From: NTSB
To: FAA
Date: 6/7/1985
Response: We are pleased to receive the FAA's detailed study of bird ingestions into large high bypass ratio turbine aircraft engines, and to learn that the FAA is now reviewing data for an early resolution of this recommendation. Pending the FAA's further response, this recommendation remains classified in an open--acceptable action status.

From: FAA
To: NTSB
Date: 5/10/1985
Response: FAA LTR: ENCLOSED FOR THE BOARD'S INFORMATION IS A COPY OF "A STUDY OF BIRD INGESTIONS INTO LARGE HIGH BYPASS RATIO TURBINE AIRCRAFT ENGINES." THE FAA'S TECHNICAL CENTER CONDUCTED A WORLDWIDE STUDY OF BIRD INVESTIGATIONS BY LARGE, HIGH BYPASS-RATIO TURBOFAN ENGINES. THE STUDY INCLUDED ALL KNOWN INGESTIONS OF ALL ENGINES OF THIS TYPE IN SERVICE, AND COVERED THE PERIOD FROM MAY 1, 1981, THROUGH JUNE 3, 1983. THE TECHNICAL CENTER HAS ANALYZED THIS DATA (IN ORDER TO CHARACTERIZE THE BIRD STRIKE ENVIRONMENT) AND PREPARED THIS REPORT. WE ARE IN THE FINAL PLANNING STAGES FOR THE FAA'S COURSE OF ACTION RELATIVE TO THIS ISSUE. WE WILL ADVISE THE BOARD IN ABOUT 60 DAYS OF OUR PROGRESS OR FURTHER ACTIONS.

From: NTSB
To: FAA
Date: 5/23/1984
Response:

From: NTSB
To: FAA
Date: 3/22/1982
Response: We appreciate the information provided in your reply of December 10, 1981, regarding the ongoing process for collecting standardized data to allow proper analysis of bird ingestion hazards for high bypass turbofan engines. This recommendation will remain classified Open--Acceptable Action until we receive the final study report and your decision regarding rulemaking action.

From: FAA
To: NTSB
Date: 12/10/1981
Response: FAA LTR: THE FAA IS IN THE PROCESS OF COLLECTING STANDARDIZED DATA TO ALLOW PROPER ANALYSIS OF BIRD INGESTION INTO LARGE HIGH BYPASS RATIO TURBOFAN ENGINES. CONTRACTS HAVE BEEN AWARDED TO THE GENERAL ELECTRIC COMPANY, PRATT & WHITNEY AIRCRAFT GROUP, AND ROLLS-ROYCE, INC., TO OBTAIN INFORMATION REQUIRED TO EVALUATE THIS NTSB RECOMMENDATION. EACH COMPANY HAS IDENTIFIED AN ENGINEERING TEAM TO INVESTIGATE SIGNIFICANT BIRD INGESTION INCIDENTS. WHEN AN INCIDENT OCCURS, THE TEAM WILL BE DISPATCHED TO THE SCENE TO OBTAIN INFORMATION ON KINDS OF BIRDS, NUMBER OF BIRDS, THRUST LOSS, DEGREE OF ENGINE AND AIRPLANE DAMAGE, ETC. EACH COMPANY WILL CONDUCT ITS OWN ENGINE INVESTIGA TIONS OVER A PERIOD WHICH MAY BE EXTENDED TO TWO YEARS IN AN ATTEMPT TO GATHER SUFFICIENT DATA FOR A STATISTICALLY VALID SAMPLE. A FINAL REPORT WILL BE PREPARED AND A COPY WILL BE FORWARDED TO THE BOARD. THE FAA WILL TAKE APPROPRIATE REGULATORY ACTION IF MEANINGFUL DATA ARE OBTAINED WHICH JUSTIFY THE AMENDMENT OF EXISTING STANDARDS.

From: NTSB
To: FAA
Date: 12/3/1980
Response: We note that the FAA has taken steps to establish a special project to obtain meaningful data necessary for the resolution of this recommendation. We thank the FAA for actions taken thus far and would appreciate being kept informed of the results of the special project. Safety rec. A-76-64 remains in an Open--Acceptable Action status.

From: FAA
To: NTSB
Date: 10/30/1980
Response: FEDERAL AVIATION ADMINISTRATION LTR: THE FAA ACKNOWLEDGES THE NEED FOR BETTER DATA RELATING TO THE NUMBER AND SIZES OF BIRDS BEING INGESTED. BECAUSE THE NORMAL REPORTING ACTIVITY OF THESE EVENTS DOES NOT USUALLY PROVIDE INFORMATION OF THIS KIND, THE FAA HAS TAKEN THE INITIAL STEPS TO ESTABLISH A SPECIAL PROJECT TO OBTAIN THE NEEDED DATA. THE FAA WILL TAKE APPROPRIATE ACTION IF STATISTICALLY MEANINGFUL DATA ARE OBTAINED WHICH JUSTIFY THE AMENDMENT OF EXISTING STANDARDS.

From: NTSB
To: FAA
Date: 7/30/1980
Response: This recommendation has been kept in an Open--Acceptable action status on the understanding that it is being resolved through the regulatory process. In order to evaluate its progress and update the public docket, we would appreciate an updated status report.

From: FAA
To: NTSB
Date: 4/26/1976
Response: This is to keep you apprised of developments with regard to your safety recommendations A-76-59 thru 64, as requested in your letter of April 9. As a first step, a general notice was developed and transmitted to all regions to implement a 60-day special emphasis program designed to identify airports having bird problems and to initiate action directed at alleviating the hazards at these airports. The GENOT included a list of available publications to assist field personnel in the formulation of local programs. A copy of this GENOT is enclosed. We will keep you informed of further developments.

From: FAA
To: NTSB
Date: 4/2/1976
Response: (76/07/26) CONSISTENT WITH YOUR RECOMMENDATION, THE AGENCY IS IN THE PROCESS OF SCHEDULING A REGULATORY REVIEW WITH ALL INTERESTED PARTIES TO IDENTIFY AREAS NEEDING POSSIBLE REVISION IN FAR 33. SPECIAL ATTENTION TO FAR 33.77 WILL BE GIVEN.