Download ETM627F14 Recall Airworthiness Directive Steve Warren

Product Recall – Airworthiness Directive (AD)
 What: FAA issued a telegraphic Amendment 39-11847 to Airworthiness Directive (AD)
2000-03-51. The actions specified in this AD are intended to prevent the loss of pitch trim
capability due to excessive wear of the jackscrew assembly of the horizontal stabilizer, which
could result in loss of vertical control of the airplane. All Model DC-9, Model MD-90-30,
Model 717-200, and Model MD-88 airplanes; certificated in any category are affected by
this recall (AD).[1,2]
 Recall Date: July 28, 2000 (compliance required by date - August 23, 2000) [1]
 Why: This AD amendment is prompted by numerous reports from operators that indicate
instances of metallic shavings in the vicinity of the jackscrew assembly and gimbal nut of the
horizontal stabilizer which may indicate excessive wear in the jackscrew assembly. [1]
 Incidents: On January 31, 2000 Alaska Airlines flight 261, a McDonnell Douglas MD-83
(MD-83), crashed into the Pacific Ocean about 2.7 miles north of Anacapa Island,
California. This incident resulted in the deaths of the 2 pilots, 3 cabin crewmembers, 83
passengers as well as the destruction of the airplane by impact forces [2]. Cause of crash –
failure of the stabilizer jackscrew assembly.
 Number of Units Sold: 2,439 units delivered from 01APR63 thru 23Nov2004 [3].
ETM627 Steve Warren – Airworthiness Directive Boeing DC-9, MD-88/90, 717-200
Nov. 30, 2014
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Management Issues
 Recognition of Problem: From August 13 to August 23, 1995, a nine-member Federal
Aviation Administration (FAA) National Aviation Safety Inspection Program (NASIP) inspection
team reported 16 noncompliance findings relative to Alaska Airlines operations, airworthiness,
flight training and flight crew weather guidance. Even with these findings, Alaska Airlines
transitioned from the FAA”s existing oversight system, the Program Tracking and Reporting
System (PTRS), to the Air Transportation Oversight System (ATOS) in October 1998. The
implementation of the FAA’s ATOS program resulted in a decrease in surveillance when an
increase in surveillance was probably needed.
 Speed of Response: The response to mitigate further incidents was relatively rapid. All of the
aircraft affected by this AD have to be grounded if they are not in compliance by the AD due
date. Aircraft grounding results in a significant loss of revenue so airlines are typically quick (but
albeit somewhat reluctant at times) to comply with the AD by the due date.
 Responsibility: While there are several events that contributed to the failure of the jackscrew
assembly and the resulting loss of lives, the main cause of failure was the absence of required
lubricant. Alaska Airlines management failed to take steps necessary to establish a culture of
compliance among it’s maintenance departments to ensure that Boeing’s maintenance
instructions for the jackscrew assembly were adhered to.
ETM627 Steve Warren – Airworthiness Directive Boeing DC-9, MD-88/90, 717-200
Nov. 30, 2014
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Impact of Recall
 Legal Consequences: As a result of a FAA investigation, Alaska Airlines was fined
$988,500 on Dec. 4, 2000 for multiple violations on several jets that were returned to
service with multiple maintenance problems. Boeing and Alaska Airlines have both
conceded liability for the crash of flight 261 and as of 2003 have settled 87 of the 88
lawsuits against them totaling several million dollars. [4,5]
 Reputation: The incident seems have little or no visible impact on the reputation of
The Boeing Company. The impact to Alaska Airlines is probably more noticeable. This is
likely due to the attention they received from the regulating authorities for making
changes to their inspection procedures/intervals in order to make a profit without
regard for the safety of the passengers.
 Sales: Fortunately for Boeing, the sale of its commercial airliners were not adversely
impacted by this recall. This may be because of Boeing’s history of airplane reliability
and safety as well its willingness to cooperate with the FAA and NTSB in investigations
such as the one surrounding the loss of this MD-83 aircraft.
ETM627 Steve Warren – Airworthiness Directive Boeing DC-9, MD-88/90, 717-200
Nov. 30, 2014
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Technical Issues
Some of the technical issues that contributed to the failure of the horizontal stabilizer trim
system from a mechanical and aerospace engineering standpoint are:
o lack of a fail safe design in the horizontal stabilizer drive system. The acme screw
threads that drives the horizontal stabilizer up and down are prone to wear due to
friction. Undetected excess wear reduces the cross sectional area of the threads
resulting in a loss in load carrying capability which lead to a catastrophic failure of the
system. A fail safe feature incorporated into the design would have prevented the
catastrophic loss of the aircraft.
o Boeing believed that the safety of the system could be assured by periodic inspection
and re-lubrication and was unaware of the fact that Alaska Airlines increased the
periodic inspection intervals by 400% (from 600 to 2400 flight hrs.). This was done
without any substantiating engineering data from Boeing or from their own internal
engineering office.
o the inspection procedure was difficult to accomplish and required that highly skilled
maintenance personnel perform the task. Even the most highly trained and proficient
people make mistakes from time to time. In light of this, Boeing’s decision to use
inspection to ensure safety of a extremely critical component on the aircraft was not
very conservative. While schedule and cost are definitely factors that influence design
of aerospace components, engineers have the ethical responsibility to ensure the
safety of the public and therefore should not allow cost and schedule to drive their
decision making.
ETM627 Steve Warren – Airworthiness Directive Boeing DC-9, MD-88/90, 717-200
Nov. 30, 2014
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References
[1] Federal Aviation Administration, Amendment 39-11847; AD 2000-15-15. July 28, 2000
Retrieved from:
http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgAD.nsf/AOCADSearch/6E2
8E61948DF0C1A86256A08006BFD14?OpenDocument
[2] National Transportation Safety Board /Aircraft Accident Report (NTSB/AAR-02/01)
(2002). Aircraft Accident Report, Loss of Control and Impact with Pacific Ocean,
Alaska Airlines Flight 261, McDonnell Douglas MD-83, N963AS, About 2.7 Miles
North of Anacapa Island, California January 31, 2000. Retrieved from
http://www.ntsb.gov/doclib/reports/2002/AAR0201.pdf
[3] The Boeing Company’s Orders and Deliveries webpage, User Defined Reports page,
Retrieved from:
http://active.boeing.com/commercial/orders/index.cfm?content=userdefinedselectio
n.cfm&pageid=m15527
[4] Bowermaster, David. "Alaska Faces FAA Safety Fine." The Seattle Times Business &
Technology. The Seattle Times, 10 Jan. 2006. Web. 29 Nov. 2014. Retrieved from
http://seattletimes.com/html/businesstechnology/2002730408_alaska10.html
[5] Kravets, David. "All but One Suit Settled in Flight 261 Crash." Seattlepi.com. The
Associated Press, 3 July 2003. Web. 29 Nov. 2014.
http://www.seattlepi.com/business/article/All-but-one-suit-settled-in-Flight-261crash-1118595.php.
ETM627 Steve Warren – Airworthiness Directive Boeing DC-9, MD-88/90, 717-200
Nov. 30, 2014
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