The Investigation Process Research Resource Site
A Pro Bono site with hundreds of resources for Investigation Investigators
Home Site Guide FAQs Tutorials Old News Contribute Forums

. . . .. . . . . . . . last updated 8/8/09
INVESTIGATING
INVESTIGATIONS

to advance the
State-of-the-Art of
investigations, through
investigation process
research.



Research Resources:

Search site for::


Launched Aug 26 1996.

  ( Go to ALPA Petition )

 

National Transportation Safety Board
Washington, D.C. 20594

May 4, 1995




Captain H. G. Gibson
Petition for Reconsideration
Aircraft Accident - Trans World Airlines, Inc.,
Boeing 727-31, N84OTW, Near Saginaw, Michigan
April 4, 1979
(NTSB-AAR-8 1-8)

RESPONSE TO PETITION FOR RECONSIDERATION

In accordance with the Safety Board’s rules (49 CFR Part 845), the Safety Board has considered the May 2, 1991 Petition for Reconsideration 1 in the aviation accident involving a Trans World Airline, Inc. (TWA) Boeing 727-31, N84OTW, near Saginaw, Michigan, on April 4, 1979. Based on its review of the petition and the facts derived during the course of the investigation and subsequent reviews, the National Transportation Safety Board denies the petition in its entirety.

On June 9, 1981, the Safety Board determined that the accident occurred after the airplane entered an uncontrolled maneuver at 39,000 feet while near Saginaw, Michigan. The airplane descended to about 5,000 feet in 63 seconds before the flightcrew regained control and made an emergency landing at Metropolitan Airport, Detroit, Michigan. The Safety Board’s analysis of the evidence indicated that the uncontrolled maneuver began after the leading edge slats were retracted and the airplane’s No. 7 leading edge slat on the right wing remained in the extended or a partially extended position. The isolated extension of the No. 7 leading edge slat resulted in a roll which led to a reduction in the airplane’s lateral control margin to zero or less. The loss of lateral control was the result of a combination of the extended slat, Mach number, angle of attack, and sideslip. The airplane entered a descending right spiral, and control of the airplane was regained only after the No. 7 slat was torn from the airplane.

1Submitted as “petition to reopen the investigation, hold a public hearing, and reconsider findings of probable cause.”
2629F



The Safety Board’s investigation revealed no evidence of irregularity, malfunction or failure of the airplane’s ffight control, autopilot, hydraulic, or flap systems that might have caused or contributed to a lateral control problem. Further, there was no evidence of any combination of failures or malfunctions in the airplane’s ffight control system that would have caused an unscheduled extension of the No. 7 leading edge slat by itself.

In adopting its report, the Safety Board detemiined that the probable cause of the accident was, “the isolation of the No. 7 leading edge slat in the full or a partially extended position after an extension of the Nos. 2, 3, 6, and 7 leading edge slats and the subsequent retraction of the Nos. 2, 3, and 6 slats, and the captain’s untimely flight control inputs to counter the roll resulting from the slat asymmetry. Contributing to the cause was a preexisting misalignment of the No. 7 slat which, when combined with the cruise condition airloads, interfered with the retraction of that slat. After eliminating all probable individual or combined mechanical failures or malfunctions which could lead to slat extension, the Safety Board determined that the extension of the slats was the result of the flightcrew’s manipulation of the flap/slat controls. Contributing to the captain’s untimely use of the flight controls was distraction due probably to his efforts to rectify the source of the control problem.” Three Board Members voted to adopt the report; two Members did not participate. Member Francis McAdams, while voting to adopt the report, filed a concurring and dissenting statement.

On January 11, 1983, the Air Line Pilots Association (ALPA) submitted a Petition for Reconsideration of probable cause and a request to reopen the investigation. The Petitioner contended that it was likely that there was a mechanical failure of the No. 7 slat actuator which resulted in uncommanded extension. On June 24, 1983, and August 28, 1983, Petitioner provided supplemental submissions concerning slat anomalies and the validity of using the Flight Data Recorder (FDR) data to make aerodynamic drag calculations.

On December 15, 1983 the Safety Board denied the petition in its entirety. The denial stated “Petitioner has provided no new evidence in either its petition or the supplements thereto to establish a valid possibility of a mechanical failure of the Ronson actuator piston on the accident airplane. Finally, Petitioner has provided no information to show that the Board’s findings as to the facts, conditions, or circumstances of the accident are erroneous, or that the Board’s conclusions regarding the probable cause of the accident are incorrect.” At that time, the five Safety Board Members unanimously denied the petition.

On October 9, 1990, ALPA submitted another Petition for Reconsideration of probable cause. This petition consists of 116 pages and claims that the Safety Board and all parties to the investigation erroneously assumed that the No. 7 leading edge slat, which separated from the airplane in flight, was the initiating cause of the accident. ALPA stated that it now believes that the previous premise is erroneous. In a cover letter to its petition, ALPA stated that a malfunction in the rudder control system most likely contributed to the initial upset. The response to the ALPA petition is being handled separately in a manner independent of the subject petition from Captain Gibson.

On December 2, 1991, Trans World Airlines, Inc., filed a petition to reopen the investigation, hold a public hearing, and reconsider the probable cause in the subject accident. TWA’s stated purpose of the petition was to “finally put to rest the questions -raised in the petition of Captain Gibson...” The TWA petition is also being handled independent of the subject petition from Captain Gibson.

The Petitioner presents eight issues in the Petition, Part One, entitled, “How Problems with the Boeing 727 Flight Controls Were Covered Up in NTSB Investigation.” They are as follows:

Issue No. 1, CVR system checkouts,

Issue No. 2, Rumor of slat extension by crew generated by NTSB Investigator-in-Charge,

Issue No. 3, Boeing’s dogma that is impossible for slats on its 727 to deploy accidentally,

Issue No. 4, Slat deployment in this case did not occur at 39,000 feet at the beginning of the upset,

Issue No.5, Boeing discredits its scenarios...but they remain in the NTSB report and finding,

Issue No.6, Boeing writes the probable cause,

Issue No.7, Boeing and NTSB destroy evidence, and

Issue No.8, Crew participation frustrated.

Additional issues are presented in Part Two of the petition entitled, “How Design Defect in Autopilot and Other Control Problems with the Boeing 727 was Revealed Despite NTSB Investigation Coverup.” They are as follows:

Issue No. 9, No. 7 slat extension was the result of the dive rather than cause, Issue No. 10, Extended No. 7 slat could not have caused the upset, Issue No. 11, TWA concealed from the NTSB a siniilar control problem.

Issue No. 12, Publicity surrounding ALPA’s 1990 petition leads to discovery of other problems,

Issue No. 13, “Buzz” as a result of outboard aileron bolt failure with the possible yaw damper and rudder actuating system malfunctions,

Issue No. 14, Boeing 727 grounded/split rudder condition,

Issue No. 15, Control problems that continue to affect Boeing 727.

The following discussion addresses the alleged new evidence and/or errors in analysis in the order presented. No. 1, the cockpit voice recorder (CVR). Petitioner states, “it is not even known whether the recorder system was functioning as intended or whether it was influenced by electrical anomalies following the emergency landing.”

The Safety Board recognizes that the CVR on board the accident airplane, with its 30-minute recording duration, did not contain contemporaneous information about the accident scenario. The only audio evidence from the CVR that was available to the investigation was a brief crew conversation that was detemiined to have taken place after the airplane had landed in Detroit As a result, the Safety Board concludes that the CVR information is largely irrelevant to the investigation and should not be a subject for reconsideration.

No. 2. Petitioner states, “Rumor of slat extension by crew generated by NTSB investigator-in-charge becomes foundation for Board’s findings of probable cause.” The “new evidence” presented by the petitioner is a series of references to an October 15, 1979 Aviation Consumer magazine article and testimony given by the Safety Board Investigator-in-Charge in an April 1982 deposition for a civil damage case.

With regard to issue No. 2, Safety Board analysis of the substance of these articles and a transcript of the testimony indicates that they do not add substantive material facts to the investigation. As a result, the Safety Board concludes that this material does not constitute “new evidence” on which to base a reconsideration.

No. 3. Petitioner states, “Boeing’s dogma that it is impossible for slats on its 727 to deploy accidentally.” Petitioner submits as “new evidence” records of eight instances of unscheduled slat deployments on Boeing 727 flights occurring between January 12, 1978, and February 28, 1989.

With regard to issue No. 3, the Safety Board addressed the subject of the unscheduled extension of leading edge slats in the Board’s Aircraft Accident Report AAR-81-8, paragraphs 1.16.1 and 1.17.2. These anomalies have occurred for a variety of reasons. In each instance the flight crew has recognized the condition and taken corrective action to control the flight path. These events are part of a continuing airworthiness effort by the Federal Aviation Administration (FAA) and the manufacturer. As a result, the Safety Board concludes that this material, as serious as it may appear, does not constitute “new evidence” on which to base a reconsideration.

No. 4. Petitioner postulates that slat deployment in this case (the accident) did not occur at 39,000 feet at the beginning of the upset, but close to 12,000 feet near its end.

Petitioner offers a statement, “When the landing gear was extended, it ruptured system A hydraulics, which according to Boeing, is what holds the slats in.” Petitioner does not provide any supporting evidence for the theory at this point however, the reader is advised that, “All of this is detaiied in Part II of this petition.”

With regard to issue No. 4, the Safety Board’s response to this subject appears after material presented by the petitioner in Part II, issue No.9.

No. 5. Petitioner states that “Boeing’s engineers discredit its “scenarios” about why captain unable to promptly recover control...but they remain in NTSB report and finding.” Petitioner claims under the heading of “new evidence” that, “it was Boeing’s reading of the flight data recorder (FDR)--not Captain Gibson-- that was “spatially disoriented.” Petitioner presents material which he describes as “fictional scenarios” which were allegedly used in an investigative coverup. However, petitioner does not present new material to substantiate a claim of erroneous findings regarding the reading of the FDR or the detemiination of the flight path.

With regard to issue No. 5, the Safety Board’s Aircraft Accident Report, AAR-81-8, addresses the subject within the Analysis section, paragraph 2.5, Loss of Control. The material presented therein was prepared by Safety Board staff using a variety of investigative group inputs and the professional knowledge of flight test and aircraft performance engineers. Analysis of the flight path contains neither a reference to a roll maneuver of right - then left to 220 degrees - then right, nor does it refer to any “overcotrol” theory. The Safety Board’s analysis of the flightpath indicates that, “At 2147:45, the aircraft was in a right bank of about 35 degrees, after which it rolled rapidly left to near a wings level attitude. About 2147:47, the aircraft began to roll again to the right,...” The Safety Board believes that the analysis of the flight path is as accurate and correct as can be detemiined using the type of FDR that was installed in the accident airplane. As a result, and lacking evidence to the contrary, the Safety Board concludes that the petitioner has not presented material on which to base a reconsideration.

No. 6. Petitioner asserts “Boeing writes Board’s finding of probable cause.” As new evidence, petitioner asserts that words prepared by the Boeing company were paraphrased by the Safety Board report writer and adopted by the Board.

With regard to issue No. 6, 49 Code of Federal Regulations (CFR) 831.14 and 845.27, relating to investigations, provide and the Safety Board actively encourages the submission of proposed findings and probable cause statements. It is not unusual for the Safety Board to adopt wording that may be very similar to the submittal of one or more parties. It is within the Board’s prerogative and it is, indeed, an obligation of the Safety Board Act to provide the best statement of probable cause from whatever source. As a result, the Safety Board concludes that the Petitioner has not presented material on which to base a reconsideration.

No. 7. The Petitioner charges, “Boeing and NTSB investigator destroyed evidence.

The Safety Board practices regarding the return of parts that have been in the Safety Board’s custody to the aircraft owner or the owner’s representative have evolved over tinie to a formalized procedure. Likewise, investigators’ source material, such as witness statements, reports, and photos that are used in the preparation of a formal report, are covered by updated procedures that set forth what should be entered into the public docket. With regard to the physical evidence related to issue No. 7, the Safety Board believes that it is more appropriate to characterize the handling of those items by the Investigator-in-Charge and the Boeing engineering personnel as disposal of excess material no longer considered necessary for the continuing investigation. As a result, the Safety Board recognizes that, by current standards, such material would be handled differently. However, now lacking the evidence, and any evidence of intent, the Safety Board concludes that the petitioner has not presented material on which to base a reconsideration.

No. 8, Crew participation fnistrated. During the investigation, crew members were formally deposed on two occasions. They were represented by their employer and their labor organization at all times. Investigative activity was undertaken in the traditional group manner with the participation of representatives of the ffightcrew’s employer and labor organization as parties to the investigation. In addition, 49 CFR 831.14 provides those concerned persons with an avenue through which to communicate directly with the Safety Board. The flightcrew did not avail themselves of this opportunity during the progress of the investigation. However, it should also be noted that it is not the practice of the Safety Board to invite or permit the involved crew members to participate actively as a member of an investigative group during the investigation process.

With regard to issue No. 8, the Safety Board believes that there was ample opportunity for the flightcrew to have made its views known during the investigative process either directly, or through their union or company representatives; however, they chose not to do so. As a result, the Safety Board concludes that the petitioner has not presented material on which to base a reconsideration.

No. 9. Petitioner states No. 7 slat extension was the result of dive rather than its cause. Petitioner refers to a portion of the Boeing Company’s report that states “...with no pre-existing damage, that slat would have departed the aircraft when its speed reached 363 KIAS when the aircraft descended to approximately 31,500 feet.”

As part of the research directed toward this reconsideration, the Boeing Company on January 11, 1993, provided the Safety Board with a revised Figure B.2.1(7), Estimated Time of Slat Separation, which corresponds with the discussion in the Boeing Report, paragraph B.2.2.1.2. That discussion states that slat separation and departure could occur between 360 and 400 knots Equivalent Air Speed.

Petitioner theorizes that the No. 7 slat did not fail until the end of the dive maneuver. Offered as evidence are the ground trail of debris and the ability of the ffightcrew to extend the landing gear with “A” system hydraulic pressure.

Petitioner advances the theory that, “Had the No. 7 slat departed the aircraft early in the dive, at 31,500 feet as calculated by the Boeing Company, then “A” system hydraulic pressure could. not have been available to extend the landing gear.”

Petitioner’s theory appears to be based on the premise that a complete failure of hydraulic system “A” is coincident with the separation of the No. 7 slat. This is not the case. Due to the small diameter of the hydraulic lines in the leading edge slat system, the hydraulic system operating pressure of 3,000 pounds per square inch (psi) will remain available after the system has been breached until the reservoir is drained, a period of several niinutes.

Investigators on scene in Detroit found the area aft of No. 7 slat bathed with hydraulic fluid. However, no such bathing or evidence of escape of a considerable quantity of hydraulic fluid was observed in the wheel well.

Petitioner’s statement regarding the extension of the landing gear also indicates a general assumption that the “A” hydraulic system is necessary to “extend” the landing gear. While this statement is true regarding an overall systems description, the statement requires operational clarification. When the landing gear handle is moved to the down position while positive “G’s” are applied to the airframe, the main landing gear will extend by themselves provided there is sufficient hydraulic pressure available to (1) open the internal gear door actuator locks and (2) open the landing gear uplocks. It should also be noted that opening the gear doors causes fluid to be displaced into the return lines, thereby temporarily “increasing” system quantity.

The Safety Board believes that the time interval between the loss of No. 7 slat (with concurrent hydraulic fluid escape) and the movement of the gear handle to the down position was short enough that sufficient system “A” hydraulic pressure remained to open the gear door actuator locks and the landing gear uplocks. Thereafter, positive “G’s” provided sufficient force to extend (and to overextend and damage) the main landing gear. However, insufficient hydraulic fluid remained in the system to bathe the landing gear area from the hydraulic line when it ruptured.

With regard to issue No. 9, Safety Board review indicates that the Analysis contained in Aircraft Accident Report AAR-81-8 was based on an appropriate speed range and appropriate reference to the degree of damage noted on the slat actuator and landing gear components as they relate to the hydraulic system “A” of the accident airplane. As a result, the Safety Board concludes that the petitioner has not presented material on which to base a reconsideration.

No. 10. Petitioner quotes the following, “The Boeing Company fuither stated that an extension of the No. 7 leading edge slat at .80 mach and 39,000 feet would have been easily controllable requiring only approximately half lateral control authority to counter the right rolling movement.”

The Safety Board concurs with the above statement. However, the petitioner goes on to present a statement of conclusion, “Therefore, an extended No. 7 leading edge slat could not have caused the upset.” However, the petitioner does not offer any basis in fact for this conclusion.

With regard to issue No. 10, the Safety Board analysis of the accident indicated that the asynimetrical slat condition resulting from the extended No. 7 slat was part of a series of events that led to the flightcrew’s loss of aircraft control. The Safety Board’s probable cause statement recognizes a series of events, including slat asyninietry and, in addition, “the captain’s untimely flight control inputs to counter the roll resulting from the slat asymmetry.” Thus, in these circumstances, the Safety Board concludes that the petitioner has not presented material on which to base a reconsideration.

The following discussion addresses the new evidence and/or errors in analysis as presented in the Petition with regard to issue No. 11. Petitioner states that “TWA concealed from NTSB that the same aircraft previously experienced a similar control problem.’’

The Safety Board has reviewed the event of May 23, 1977, presented by the petitioner as (1) a siniilar control problem, and (2) in the sanie aircraft. The control problem experienced on May 23, 1977, is characterized by the Check Aimian Captain as an “autopilot disconnect” malfunction. The flying pilot, another Check Airman, described the condition as follows, “...the autopilot apparently disconnected (the autopilot paddles dropped to the disengaged position), but the flight controls became extremely difficult to manipulate in roll, and there was no annunciation provided to indicate the source of the problem.”

The Safety Board notes that the accident scenario which took place on B-727 N840TW did not include any mention of “difficult to manipulate” flight controls. On the contrary, the captain of the accident flight offered in his testimony that “I had full (left) aileron input and full left rudder input also, and the aircraft was still rolling to the right.”

The Safety Board believes that the analysis of the flightpath of the accident airplane derived from the FDR data and the later flight test, as presented in AAR-81-8, is correct. On the basis of the evidence presented by the petitioner as comparable, the Safety Board is not able to characterize the events as similar control problems.

The petitioner characterizes activity surrounding the 1977 event as “concealed” from the Safety Board. The Safety Board does not have evidence of concealment of facts. In any event, the Safety Board does not believe that the 1977 event was a “similar control problem.”

Also, there is conflicting information in the Petition for Reconsideration and associated affidavits related to which airplane experienced the 1977 autopilot disconnect malfunction. The Safety Board recognizes the inconsistencies in the archived information. However, with regard to issue No. 11, the Safety Board must evaluate the information that can be gained to support the factual record of investigation by pursuit of these inconsistencies. Regardless of which aircraft was involved in the 1977 incident, the Safety Board believes that the 1977 event was not a similar control problem as that experienced during the accident flight. As a result, the Safety Board concludes that the petitioner has not presented material on which to base a reconsideration.

No. 12. Petitioner alleges that “Publicity surrounding ALPA’s 1990 petition leads to discovery of other Boeing 727 control problems.” Petitioner presents a list of nine events and states, “In every case, when the pilot tried to bank the airplane or level the wings, he encountered significant resistance and the aircraft wanted to go in the opposite direction.”

The Safety Board recognizes that there have been and will be recorded instances of autopilot malfunctions. However, in each of the incidents presented by the petitioner, the flightcrew was able to overcome the difficulties and accomplish a successful landing. Also, following maintenance actions, the aircraft were returned to service. Petitioner alleges that the December 1989 TWA incident is of particular significance as it is a repeat of Flight 841 (the accident flight) at 37,000 feet.

The Safety Board does not agree. In the 1989 incident, forceful full right aileron input was required, and the malfunction was indicative of an autopilot malfunction that was manageable by the flightcrew. On the contrary, in the accident circumstances, the flightcrew debriefings, and statements and depositions related to the flight control inputs indicate that full and unimpeded movement of all flight controls was possible and applied by the crew. With regard to issue No. 12, the results of flight tests subsequent to the accident, in which full control input was available and applied, offered close comparisons with the FDR data from the accident airplane. As a result, the Safety Board concludes that the Petitioner has not presented evidence of similar control problems in other airplanes on which to base a reconsideration.

No. 13. Petitioner suggests that the “buzz and tuniing” at the beginning of the accident ffight upset was the result of outboard aileron bolt failure in flight and aileron “float” upwards. Petitioner further suggests that resultant yawing movement may have resulted in a malfunction of the yaw daniper and nidder actuating system.

The Safety Board recognizes that a malfunction of either of these systems would produce recognizable yawing moments and roll response. However, the Petitioner has not provided any evidence that yawing moments associated with these systems were observed by the flightcrew or the passengers. Also, such yawing moments were not identifiable on the FDR. However, flight tests conducted after the accident did produce FDR vertical acceleration traces as a result of flap movement that were consistent with the evidence from the accident airplane’s FDR. Likewise, drag coefficients resulting in speed changes on the flight test airplane following flap configuration changes were consistent with the speed changes observed on the FDR indicated airspeed traces from the accident airplane. With regard to issue No. 13, the Petitioner has not provided any new evidence to substantiate the premise that a malfunction of the yaw damper or the nidder actuating system was present on the accident airplane. As a result, the Safety Board concludes that the Petitioner has not presented material on which to base a reconsideration.

No. 14. Petitioner states “Boeing 727 grounded as this petition was being formulated.” Petitioner details a split rudder condition.

The Safety Board notes that according to the maintenance report associated with this event, the malfunction described above ceased when the autopilot was disengaged. Petitioner implies that any manner of flight control anomaly should be regarded as an event similar to the flight control difficulties experienced on the accident flight.

The Safety Board is concerned that any flight control anomaly has the potential to become a serious hazard to flight. However, the Board attempts to keep such anomalies in perspective regarding the airworthiness of the affected aircraft. With regard to issue No. 14, the Safety Board’s analysis of the reported event indicates that the flight condition was fully controllable and correctable. As a result, the Safety Board concludes that the Petitioner’s statement describing a split rudder condition and unconimanded yaw does not, in itself, constitute “new evidence” on which to base a reconsideration of probable cause.

No. 15. The Petitioner suggests that control problems that affected TWA flight 841 continue to affect B727s.

With regard to the overall focus of issue No. 15, and alleged control problems that continue to affect B-727s, petitioner does not provide specifics or evidence. The Safety Board’s analysis indicates that the charge of continuing problems siniilar to those evident on the accident flight has not been verified. As a result, the Safety Board concludes that the Petitioner’s presentation of continuing control problems does not constitute “new evidence” on which to reopen the investigation or base a reconsideration of probable cause.

Also in the Petition in the Nature of Mandamus filed January 13, 1995, petitioner alleges that there is “a dangerous design defect in both the Boeing 727 and Boeing 737...,” and that investigation of the March 3, 1991, Boeing 737 accident at Colorado Springs, Colorado revealed, “Boeing 727s and Boeing 737s share a common control defect.”

Comparative review of the B-727 and B-737 rudder systems indicates basic design differences. The B-727 has independent upper and lower rudders, each connected to an independent power control unit (PCU). Each of the PCU’s control valves are of a single spool design. The upper PCU is powered by the “B” hydraulic system and the lower PCU is powered by the “A” hydraulic system. There are load limit features built into the hydraulic power sources for the PCUs. The airplane is also equipped with two yaw damper systems which function independently through the respective upper or lower PCUs. Rudder travel is +27.5 degrees; however, yaw damper authority is limited to ±5 degrees.

The B-737, by comparison, has a single rudder surface, and one main rudder PCU of a different design. The PCU is of a dual concentric control valve design which incorporates hydraulic power from both the “A and B” hydraulic systems. The airplane also has one yaw damper system operating at the PCU, which is limited to 20 or 30, depending on the model of the airplane.

There is one similar component (with a different part number) for the B-727 and B-737 rudder system, the standby rudder actuator. However, it should be noted that in the B-727 application, the standby actuator functions only on the lower rudder. In the event of a B-727 malfunction of either the upper or lower rudder control systems or the yaw damper systems, or in the standby rudder system, sufficient lateral control authority has been demonstrated in the ffight regime encountered during the subject accident to overcome any unconimanded rudder deflections up to and including full control deflection of either the upper or lower rudder or the yaw damper system. Therefore, with respect to the theory of a common control defect between the B-727 and B-737, the Safety Board concludes that the petitioner has not presented evidence regarding this issue on which to base a reconsideration.

Finally, the airworthiness of the B-737 lateral control systems has been examined extensively as part of the ongoing investigation of the US Air 427 accident at Pittsburgh. If during the continuation of the USAir investigation, or any future accident or incident investigation, an airworthiness problem is identified that could result in a loss of control of the B-727, those findings will be analyzed in depth.

With regard to the probable cause, the Safety Board has considered the petition to reopen the investigation, hold a public hearing, and reconsider findings of probable cause. As a result, the Safety Board concludes that the Petitioner has not provided new evidence or shown that the Board’s findings as to the facts, conditions, or circumstances of the accident are erroneous, or that the Board’s conclusions regarding the probable cause are incorrect.

Accordingly, Captain H. G. Gibson’s petition for reconsideration of May 2, 1991, to reopen the investigation, hold a public hearing, and reconsider findings of probable cause is hereby denied.

Chairman HALL, Vice Chairman FRANCIS, and Member HAMMERSCHMIDT concurred in the disposition of this petition for reconsideration.