User talk:IGhhGI

Hello, were there any repairs to the #7 slat before the 1979 incident besides fixing oil leaks? My memory was that some log pages had appeared, but perhaps this story was confused with the F. T. William's late report of handling problems in 1977. Thank you, Fotoguzzi (talk) 14:03, 8 July 2012 (UTC)[reply]

= = =   //   = = =

Responding to question, 8July2012:

"... were there any repairs to the #7 slat before the ... incident ... log pages had appeared ... [?]"

ANSWER -- the "pre-existing damage" and "misalignment" of the #7 Slat was a post-mishap finding ["wreckage examination" of recovered parts found on the ground and examination of N840TW at DTW]: first cited in the NTSB's Structures Group Factual Rpt, dated May 10th, 1979, page 2 top.

Then, dated August 23, 1979, the NTSB's "Metallurgist's Factual Report" [signed by ML Marx]:

"... Examination of the No.7 slat disclosed fatigue cracking in the inboard slat track attachment area of the tee bolt and skin attach clips ..." [several paragraphs discussing metallurgical examination of pre-existing wear].--IGhhGI (talk) 21:53, 10 July 2012 (UTC)[reply]

Then cited later in the Boeing Report (Sept'79), Structures Section, pg B-1, third paragraph:

"... pre-existant damage was found in four areas. The slat #7 inboard track support structure on the slat had a fractured T-bolt after some previous fatigue crack growth, and the nearby skin support bracket angle had some fatigue cracking that merged into overload separation during the incident...."

Then, in the NTSB's final AAR81-8, pg 26, mid-page: "... metallurgical examination ... No. 7 slat inboard T-bolt ... weakened by fatigue before it failed.... wear pattern on the slat alignment hooks indicate that the slat was misaligned and that the T-bolt may have broken before the slat extended ... causing ... sag ...."

The pre-existing damage and misalignment of #7 Slat was later discussed in litigation (testimony _Wicker v. TWA & TBC_)

On slat 7 damage

Thanks, I am slowly making my way through such documents as I find. As a layman I am wondering a few things: 1) If slat #7 deployed when Circuit A was damaged by the landing gear over-extension, why wouldn't slat #2 or others also deploy? 2) Could vibration from the aileron with the broken/breaking bolt have caused slat #7 to vibrate loose from its retracted position? If I read correctly, one of two restraining hooks was not engaged at all. Thanks again. Fotoguzzi (talk) 23:16, 10 July 2012 (UTC)[reply]

ANSWER to questions of July10th

Question posed, dated July 10th, 2012:

"... If slat #7 deployed when ... [Hydraulic System] "A" was damaged [pressure dropped from 3000psi to zero psi] by the landing gear over-extension, why wouldn't slat #2 or others also deploy?"

The Boeing 727 Ops' Manual Bulletin 75-7 [OMB 75-7, March 10, 1976; Subject: "Leading Edge Slat Actuator Lock Rings"] suggested conditions that had previously pulled one or more Slat s from their Retracted position: OMB 75-7 was reprinted as AAR81-8's Appendix E, AAR pages 49 & 50. Since each B727 Slat can be held in the Retracted position by normal System "A" Hydraulic Pressure (acting against the Retract-side of the Slat Actuator), the only conditions under which a Slat could by "pulled" aerodynamically from its Retracted Position are those combined conditions listed in Boeing's OMB 75-7:

"... a failure of hydraulic System 'A', combined with a severely fractured or missing Retract Lock Ring, followed by use of Speed Brakes above Mach .80 may cause one or more slats to extend."

This combination of conditions did not exist during Crz at FL390: But AFTER the pilot Extended the MLG, the Sys "A" Hydraulic pressure failed, Spd was pegged at the high-end of the Airspeed/Mach Indicator, SpdBrks had been "deployed" [though most likely affected by "blow-down" aero-loading]. So, AFTER pilots Extended the Landing Gear, late in the dive, is the most likely phase during which all of the combination existed. This topic, Loads on a Slat, is detailed in the "alpa" Petition (of Oct'90), proposed changes to AAR Section 1.17.5: "alpa" Petition of Oct'1990 (Yorke's Analysis) Essentially, the only way for an airline to learn about a failed Retract Lock Ring (inside a Slat Actuator), was during an event that caused Hydraulic System "A" pressure to decay, while Mach>0.8M, with SpdBrks Deployed.

SECOND QUESTION posed, dated July 10th, 2012:

"... Could vibration from the aileron with the broken/breaking bolt have caused slat #7 to vibrate loose from its retracted position?"

Maybe, but Boeing denied any affect from "buffet", and denied any "flutter" due to freeplay of the RHS O/B Aileron. The NTSB's "docket" was edited by the IIC, so many of the letters from NTSB to Boeing were NOT included in that NTSB-docket. But, the Boeing reply-letter dated April 16th, 1980, acknowledges questions posed earlier by NTSB:

--  in a "letter dated Feb'12,'80" and  
-- during a NTSB-Boeing "meeting of March 18, 1980 at Boeing".

The Boeing letter of April 16th'80 is listed  in the NTSB's "docket"- index as "Boeing Report M-7210-5117-C/G", added to the docket on 6/1/81.   Boeing did NOT comment  specifically upon effects of "vibration" interacting with a damaged Retract Lock Ring inside the  #7 Slat Actuator.  Boeing did suggest that the "upfloat"  of the damaged Hinge Bolt in the  RHS Outboard Aileron (aft of #7 Slat), would affect the aero-loading on the LE Slat (similar to a deployed Spoiler/SpdBrk):

"Any free play introduced in the outboard aileron will allow upward deflection ... as a result of aerodynamic forces acting on the wing.... A calculation was made based on allowing the aileron to float until the aileron hinge moment reaches zero.... a free floating outboard aileron would result in the loss of 400 pounds of lift locally.... possible rod load changes at the No. 7 slat position ... a 9% reduction in aerodynamic load on the No. 7 Slat actuator rod."

[Letter, April 16,1980, Boeing (Prater Hogue) to NTSB (Kampschror). "727 Wing Buffet and Pressure Distribution" 8pgs, 6 graphs. "Effect of Aileron Freeplay on Slat Number 7 Rod Loads" 8 pgs, 4 graphs, 1 table.]--IGhhGI (talk) 17:38, 11 July 2012 (UTC)[reply]

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December 2016

Hello, and welcome to Wikipedia. You appear to be repeatedly reverting or undoing other editors' contributions at TWA Flight 841 (1979). Although this may seem necessary to protect your preferred version of a page, on Wikipedia this is known as "edit warring" and is usually seen as obstructing the normal editing process, as it often creates animosity between editors. Instead of reverting, please discuss the situation with the editor(s) involved and try to reach a consensus on the talk page.

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Please do not attack other editors, as you did at Talk:TWA Flight 841 (1979). Comment on content, not on contributors. Personal attacks damage the community and deter users. Please stay cool and keep this in mind while editing. This edit was not appropriate. Article talk pages are for discussion of improvements to the article, not for attacking other editors. VQuakr (talk) 23:05, 21 December 2016 (UTC)[reply]

January 2017

Please assume good faith in your dealings with other editors, which you did not do on Talk:TWA Flight 841 (1979). Assume that they are here to improve rather than harm Wikipedia. VQuakr (talk) 17:21, 26 January 2017 (UTC)[reply]

You may be blocked from editing without further warning the next time you make personal attacks on other people, as you did at Talk:TWA Flight 841 (1979). Comment on content, not on fellow editors. VQuakr (talk) 20:51, 26 January 2017 (UTC)[reply]

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