Shore Guy
30th Aug 2005, 04:52
Anyone have any additional info on this?
Background
On April 29, 2005, the FAA issued AD 2005-10-03, amendment 39-14080 (70 FR 24703, May 11, 2005), for certain Boeing Model 777-200 and -300 series airplanes. That AD requires modification of the operational program software (OPS) of the air data inertial reference unit (ADIRU) from software version part number (P/N) 3470-HNC-100-03 to software version P/N 3475-HNC-100-06 or 3474-HNC-100-07. That AD resulted from a report of the display of erroneous heading information to the pilot due to a defect in the OPS of the ADIRU. We issued that AD to prevent the display of erroneous heading information to the pilot, which could result in loss of the main sources of attitude data, consequent high pilot workload, and subsequent deviation from the intended flight path.
Actions Since Issuance of Previous AD
Since that AD was issued, we received a recent report of a significant nose-up pitch event on a Boeing Model 777-200 series airplane while climbing through 36,000 feet altitude. The flight crew disconnected the autopilot and stabilized the airplane, during which time the airplane climbed above 41,000 feet, decelerated to a minimum speed of 158 knots, and activated the stick shaker. A review of the flight data recorder shows there were abrupt and persistent errors in the outputs of the ADIRU. These errors were caused by the OPS using data from faulted (failed) sensors. This problem exists in all software versions after P/N 3470-HNC-100-03, beginning with P/N 3477-HNC-100-04 approved in 1998 and including the versions mandated by AD 2005-10-03. While these versions have been installed on many airplanes before we issued AD 2005-10-03, they had not caused an incident until recently, and the problem was therefore unknown until then. OPS using data from faulted sensors, if not corrected, could result in anomalies of the fly-by-wire primary flight control, autopilot, auto-throttle, pilot display, and auto-brake systems, which could result in high pilot workload, deviation from the intended flight path, and possible loss of control of the airplane.
Explanation of Relevant Service Information
We have reviewed Boeing Alert Service Bulletin 777-34A0137, dated August 26, 2005. The service bulletin describes procedures for installing OPS, P/N 3470-HNC-100-03, in the ADIRU.
We also have reviewed Boeing 777 Operations Manual Bulletin (OMB) CS3-3093, dated August 26, 2005, which describes operating instructions to inform the flight crew of possible heading errors following on-ground automatic realignment of the ADIRU with the OPS, P/N 3470-HNC-100-03, installed.
In addition, we have reviewed Boeing 777 OMB CS3-3155, dated August 26, 2005, which describes operating instructions to inform the flight crew of potential drift angle discrepancies on the primary flight display and the navigation display with the OPS, P/N 3470-HNC-100-03, installed.
FAA's Determination and Requirements of the Rule
We have evaluated all pertinent information and identified an unsafe condition that is likely to exist or develop on other Boeing Model 777 airplanes of this same type design. Therefore, we are issuing this AD to prevent the OPS from using data from faulted (failed) sensors, which could result in anomalies of the fly-by-wire primary flight control, autopilot, auto-throttle, pilot display, and auto-brake systems. These anomalies could result in high pilot workload, deviation from the intended flight path, and possible loss of control of the airplane. This new AD supersedes AD 2005-10-03. This new AD requires accomplishing the actions specified in Boeing Alert Service Bulletin 777-34A0137, described previously. Because these actions reintroduce the unsafe condition identified in AD 2005-10-03, this new AD also requires revising the Limitation section of the Airplane Flight Manual by inserting a copy of Boeing 777 OMBs CS3-3093 and CS3-3155, described previously.
Interim Action
We consider this proposed AD interim action. The manufacturer is currently developing a modification that will address the unsafe condition identified in this AD and AD 2005-10-03. Once this modification is developed, approved, and available, we may consider additional rulemaking
Full content at:
http://www.airweb.faa.gov/Regulatory_and_Guidance_Library/rgad.nsf/0/25F9233FE09B613F8625706C005D0C53?OpenDocument
Primarly info on the emergency AD issued 8-29-05. I just posted the lead in of the full AD with the link to full content.
Background
On April 29, 2005, the FAA issued AD 2005-10-03, amendment 39-14080 (70 FR 24703, May 11, 2005), for certain Boeing Model 777-200 and -300 series airplanes. That AD requires modification of the operational program software (OPS) of the air data inertial reference unit (ADIRU) from software version part number (P/N) 3470-HNC-100-03 to software version P/N 3475-HNC-100-06 or 3474-HNC-100-07. That AD resulted from a report of the display of erroneous heading information to the pilot due to a defect in the OPS of the ADIRU. We issued that AD to prevent the display of erroneous heading information to the pilot, which could result in loss of the main sources of attitude data, consequent high pilot workload, and subsequent deviation from the intended flight path.
Actions Since Issuance of Previous AD
Since that AD was issued, we received a recent report of a significant nose-up pitch event on a Boeing Model 777-200 series airplane while climbing through 36,000 feet altitude. The flight crew disconnected the autopilot and stabilized the airplane, during which time the airplane climbed above 41,000 feet, decelerated to a minimum speed of 158 knots, and activated the stick shaker. A review of the flight data recorder shows there were abrupt and persistent errors in the outputs of the ADIRU. These errors were caused by the OPS using data from faulted (failed) sensors. This problem exists in all software versions after P/N 3470-HNC-100-03, beginning with P/N 3477-HNC-100-04 approved in 1998 and including the versions mandated by AD 2005-10-03. While these versions have been installed on many airplanes before we issued AD 2005-10-03, they had not caused an incident until recently, and the problem was therefore unknown until then. OPS using data from faulted sensors, if not corrected, could result in anomalies of the fly-by-wire primary flight control, autopilot, auto-throttle, pilot display, and auto-brake systems, which could result in high pilot workload, deviation from the intended flight path, and possible loss of control of the airplane.
Explanation of Relevant Service Information
We have reviewed Boeing Alert Service Bulletin 777-34A0137, dated August 26, 2005. The service bulletin describes procedures for installing OPS, P/N 3470-HNC-100-03, in the ADIRU.
We also have reviewed Boeing 777 Operations Manual Bulletin (OMB) CS3-3093, dated August 26, 2005, which describes operating instructions to inform the flight crew of possible heading errors following on-ground automatic realignment of the ADIRU with the OPS, P/N 3470-HNC-100-03, installed.
In addition, we have reviewed Boeing 777 OMB CS3-3155, dated August 26, 2005, which describes operating instructions to inform the flight crew of potential drift angle discrepancies on the primary flight display and the navigation display with the OPS, P/N 3470-HNC-100-03, installed.
FAA's Determination and Requirements of the Rule
We have evaluated all pertinent information and identified an unsafe condition that is likely to exist or develop on other Boeing Model 777 airplanes of this same type design. Therefore, we are issuing this AD to prevent the OPS from using data from faulted (failed) sensors, which could result in anomalies of the fly-by-wire primary flight control, autopilot, auto-throttle, pilot display, and auto-brake systems. These anomalies could result in high pilot workload, deviation from the intended flight path, and possible loss of control of the airplane. This new AD supersedes AD 2005-10-03. This new AD requires accomplishing the actions specified in Boeing Alert Service Bulletin 777-34A0137, described previously. Because these actions reintroduce the unsafe condition identified in AD 2005-10-03, this new AD also requires revising the Limitation section of the Airplane Flight Manual by inserting a copy of Boeing 777 OMBs CS3-3093 and CS3-3155, described previously.
Interim Action
We consider this proposed AD interim action. The manufacturer is currently developing a modification that will address the unsafe condition identified in this AD and AD 2005-10-03. Once this modification is developed, approved, and available, we may consider additional rulemaking
Full content at:
http://www.airweb.faa.gov/Regulatory_and_Guidance_Library/rgad.nsf/0/25F9233FE09B613F8625706C005D0C53?OpenDocument
Primarly info on the emergency AD issued 8-29-05. I just posted the lead in of the full AD with the link to full content.