Tartarus
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Joined: Tue Jul 12, 2016 9:36 am

FAA to order AoA vane changes on 727/757/767.

Tue Jul 09, 2019 3:06 am

The FAA will mandate AoA vanes on 727/757/767 be changed due to icing causing spurious stick shaker warnings.

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Reports of nuisance stall warnings triggered by frozen angle-of-attack (AOA) vanes has led FAA to mandate replacement of the parts on Boeing 757s, 767s and 727s.

FAA, in a notice of proposed rulemaking set for publication July 9, is proposing a 36-month window for replacing affected AOA vanes—a shorter time period than Boeing recommended in alert service bulletins that target each model. Boeing issued the bulletins in the last six months.

“We have received reports of nuisance stick-shaker activation while the airplane was accelerating to cruise speed at the top of the climb,” FAA explained in the NPRM. “A review of recorded flight data and weather reports indicated that the cause of the nuisance stick-shaker activation was immobilized AOA sensor vanes, which were frozen because the heaters in the AOA sensors vanes were not sufficient to prevent ice build-up in the AOA sensor faceplate and vane.”

Water entering the vanes and freezing during takeoff can trigger the issue, FAA added.

If finalized, the rule would require inspections of nearly 1,300 US-registered 757s, 767, and 727s for certain AOA vanes. If vanes with certain part numbers are found, operators must swap them for components with different part numbers.

Boeing’s bulletins recommended compliance within 9,960 hr. for 757s, 3,470 hr. for 767s, and 2,750 hr. for 727s.

“We have determined that this compliance time will not ensure that the identified unsafe condition is addressed in a timely manner,” FAA explained. “In developing an appropriate compliance time for this AD, we considered the degree of urgency associated with addressing the subject unsafe condition, the average utilization of the affected fleet, and the time necessary to perform the modifications.”

FAA in the NPRM says swapping affected vanes is expected to take about 3 hr. per aircraft.


http://m.atwonline.com/airframes/faa-or ... 57-767-727
 
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AirKevin
Posts: 449
Joined: Wed Apr 26, 2017 2:18 am

Re: FAA to order AoA vane changes on 727/757/767.

Tue Jul 09, 2019 1:34 pm

Better start grounding them. :duck: In all seriousness, I wonder how many 727s are even still flying.
Captain Kevin
 
TTailedTiger
Posts: 1167
Joined: Sun Aug 26, 2018 5:19 am

Re: FAA to order AoA vane changes on 727/757/767.

Wed Jul 10, 2019 8:04 am

How long will this take? We can't afford to have the 727 fleet out of the skies for too long. :rotfl: :rotfl:
 
unimproved
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Re: FAA to order AoA vane changes on 727/757/767.

Wed Jul 10, 2019 11:48 am

Do wonder how the 737 managed to be excluded, as the fuselage is almost 1:1 with the 727 and these sensors have been used for quite a while it seems.
 
SteelChair
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Joined: Fri Aug 25, 2017 11:37 am

Re: FAA to order AoA vane changes on 727/757/767.

Wed Jul 10, 2019 7:13 pm

Another stupid decision by the government in the wake of a totally unrelated accident. Jobs have to be justified, budgets have to be protected.
 
strfyr51
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Joined: Tue Apr 10, 2012 5:04 pm

Re: FAA to order AoA vane changes on 727/757/767.

Wed Jul 10, 2019 9:05 pm

We've already had 3 AD Notes on AOA Vanes for Heating problems over the years, The AOA Vanes take a LOT of wear and Damage. So this is nothing new. the AOA takes about 1:45 to replace and Ops check. The question might be? Availability of NEW units...
 
zuckie13
Posts: 143
Joined: Fri Mar 02, 2018 8:23 pm

Re: FAA to order AoA vane changes on 727/757/767.

Wed Jul 10, 2019 10:53 pm

unimproved wrote:
Do wonder how the 737 managed to be excluded, as the fuselage is almost 1:1 with the 727 and these sensors have been used for quite a while it seems.


Same body shape doesn't mean they used the same part number for the vane and heater. I'd even guess that different models got different part numbers. Don't forget even the classics came out after the 757/767.
 
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fr8mech
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Re: FAA to order AoA vane changes on 727/757/767.

Thu Jul 11, 2019 12:31 am

Hell, we've already got 20% of our fleet complied with, and we started in March, and we plan to be complete by 1Q21.
When seconds count...the police are minutes away.
Unless it's expressly prohibited, it's allowed.
You are not entitled to a public safe space.
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1989worstyear
Posts: 571
Joined: Sun Dec 04, 2016 6:53 pm

Re: FAA to order AoA vane changes on 727/757/767.

Thu Jul 11, 2019 5:28 am

zuckie13 wrote:
unimproved wrote:
Do wonder how the 737 managed to be excluded, as the fuselage is almost 1:1 with the 727 and these sensors have been used for quite a while it seems.


Same body shape doesn't mean they used the same part number for the vane and heater. I'd even guess that different models got different part numbers. Don't forget even the classics came out after the 757/767.


757 and 767 are still more advanced from a technological POV than the Classics, but I can't remember if the 1982 AOA sensor LRU on the 757 and 767 puts out 429 directly like a modern 1988 design - it might be analog since serial data buses were in around in 1982.

Serial communication like ARINC 429 was unheard of in '82 (standard did not exist yet), but by '88 it became mature technology within a year (A320).

I might check some schematics if I get the chance. I'll be shocked if it's not analog.
Stuck at age 15 thanks to the certification date of the A320-200 and my parents' decision to postpone having a kid by 3 years. At least there's Dignitas...

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