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28th Mar 2019, 17:34
Replies: 908
Views: 930,792
Posted By FCeng84

With regard to the acceptability of operating...

With regard to the acceptability of operating without a particular control system feature active, it all comes down to consideration of both the consequences of not having that feature and the rate...
28th Mar 2019, 06:53
Replies: 908
Views: 930,792
Posted By FCeng84

The two AOA signals move together but with about...

The two AOA signals move together but with about 20 degrees separation. The left one is too high. MCAS was using that one during this Lion Air accident. I sure want to see the same parameters from...
28th Mar 2019, 06:38
Replies: 5,129
Views: 10,183,761
Posted By FCeng84

JR - your story about automatic retraction of the...

JR - your story about automatic retraction of the inboard leading edges at high AOA on the Falcon 900 reminds me of stall characteristics on the original 777. As an airplane approaches stall you...
28th Mar 2019, 03:19
Replies: 5,129
Views: 10,183,761
Posted By FCeng84

AOA vane position is not valid until up to an...

AOA vane position is not valid until up to an airspeed well above that for taxi. Revised MCAS logic keeps MCAS from acting at all if an AOAs signals differ by anywhere near as much as appears to have...
28th Mar 2019, 02:34
Replies: 5,129
Views: 10,183,761
Posted By FCeng84

The UAS on Lion Air resulted from the left and...

The UAS on Lion Air resulted from the left and right airspeed signals not tracking each other. This was most likely caused by the the left /right sensed AOA difference, but declaring UAS did not...
27th Mar 2019, 11:42
Replies: 5,129
Views: 10,183,761
Posted By FCeng84

Please explain what you mean by “Stall ID”. Also...

Please explain what you mean by “Stall ID”. Also please describe “737Ng Stall ID trimming”. I am very familiar with the term “Stall ID” as part of the regulations but not in this context.
Forum: Tech Log
27th Mar 2019, 02:02
Replies: 195
Views: 79,091
Posted By FCeng84

With PPRUNE page and post numbers in flux due to...

With PPRUNE page and post numbers in flux due to moderator actions within these busy / large threads I recommend referring to previous posts by entry date and time stamp. That is one thing that...
27th Mar 2019, 01:52
Replies: 908
Views: 930,792
Posted By FCeng84

STS activation will not reset MCAS. In fact it...

STS activation will not reset MCAS. In fact it may well be that MCAS has higher priority than STS such that when MCAS has inserted airplane nose down stabilizer motion STS is precluded from acting...
26th Mar 2019, 23:31
Replies: 908
Views: 930,792
Posted By FCeng84

As stated before, the consequences of all failure...

As stated before, the consequences of all failure modes must be evaluated and a hazard level assigned to each. Only when the combination of failure rate and hazard level of the consequences are...
26th Mar 2019, 23:07
Replies: 5,129
Views: 10,183,761
Posted By FCeng84

Several people have asked MCAS clarification...

Several people have asked MCAS clarification questions in response to some of my recent posts. Rather than respond to them individually I offer the following as hopeful a fairly comprehensive...
26th Mar 2019, 17:48
Replies: 908
Views: 930,792
Posted By FCeng84

Note to Moderators: Below is a copy of a post...

Note to Moderators: Below is a copy of a post that I made within the Ethiopian accident thread earlier in response a post referencing the same article as that linked above. I know that PPRUNE...
26th Mar 2019, 17:10
Replies: 5,129
Views: 10,183,761
Posted By FCeng84

One of the key elements to the baseline MCAS...

One of the key elements to the baseline MCAS logic is that it will only put in a single increment of stabilizer motion as long as no pilot trim command is given. This goes in over no more than 10...
26th Mar 2019, 16:53
Replies: 5,129
Views: 10,183,761
Posted By FCeng84

The only time that stabilizer positioning...

The only time that stabilizer positioning requires or even benefits from reference to the absolute position of the stabilizer is when on ground, preparing for takeoff. When in air, pilot commanded...
25th Mar 2019, 19:52
Replies: 5,129
Views: 10,183,761
Posted By FCeng84

Here we are 15 days and 2500+ posts into a thread...

Here we are 15 days and 2500+ posts into a thread about an accident for which we have not yet seen the FDR info nor heard anything about the crew conversations from the CVR and we are already saying...
25th Mar 2019, 05:52
Replies: 5,129
Views: 10,183,761
Posted By FCeng84

I must take issue with the statement that "MCAS...

I must take issue with the statement that "MCAS overides controls". MCAS commands the horizontal stabilizer but does not override pilot commands to that or any surface. At any time that MCAS...
25th Mar 2019, 00:44
Replies: 5,129
Views: 10,183,761
Posted By FCeng84

This depends on what you call stability. If...

This depends on what you call stability. If stability is the tendency to pitch back down in response to having pitched up, MCAS can be viewed as increasing pitch stability
25th Mar 2019, 00:08
Replies: 5,129
Views: 10,183,761
Posted By FCeng84

Please indulge my adding a few comments. Today’s...

Please indulge my adding a few comments. Today’s commercial aviation has embraced use of automation to enable optimization for performance. This has led to configurations that do not have certifiable...
24th Mar 2019, 22:28
Replies: 5,129
Views: 10,183,761
Posted By FCeng84

As expected given the Lion Air accident, most of...

As expected given the Lion Air accident, most of the focus on MCAS has been on how it behaves with the AOA signal it is using failed high. When MCAS has proper AOA data it meets the noted static...
23rd Mar 2019, 19:41
Replies: 5,129
Views: 10,183,761
Posted By FCeng84

Hopefully Boeing will make the details of the...

Hopefully Boeing will make the details of the MCAS modification clearer soon. MCAS in its original implementation would run again in the presence of AOA failed high following any amount of pilot...
23rd Mar 2019, 19:27
Replies: 5,129
Views: 10,183,761
Posted By FCeng84

Consider the situation of the airplane being...

Consider the situation of the airplane being loaded to its aft CG limit but the stabilizer trimmed full nose up or the opposite of forward CG with full nose down stabilizer. In either of these cases...
23rd Mar 2019, 16:24
Replies: 908
Views: 930,792
Posted By FCeng84

A single point failure is acceptable if the...

A single point failure is acceptable if the consequences are bounded and the failure rate is sufficiently remote. As stated before a single failure with catastrophic results is never acceptable.
Forum: Tech Log
23rd Mar 2019, 09:59
Replies: 195
Views: 79,091
Posted By FCeng84

Automation and Artificial Intelligence are not...

Automation and Artificial Intelligence are not one and the same. With automation control systems automatically respond in a predetermined manner to a combination of airplane state and pilot input....
23rd Mar 2019, 09:33
Replies: 5,129
Views: 10,183,761
Posted By FCeng84

Beyond that it is clearly a violation of the FARs...

Beyond that it is clearly a violation of the FARs for a system to have a failure mode arrived at by (1) any combination of failures whose probability is greater that 1x10E-9 or (2) any single failure...
23rd Mar 2019, 09:05
Replies: 908
Views: 930,792
Posted By FCeng84

Airplane system design is driven by a very...

Airplane system design is driven by a very rigorous process of aligning functional availability and integrity with the associated failure hazards effects. Key questions that receive careful attention...
23rd Mar 2019, 08:39
Replies: 908
Views: 930,792
Posted By FCeng84

Let me offer a couple of thoughts about 737MAX...

Let me offer a couple of thoughts about 737MAX AOA failure rates.

First, we know that the Lion Air accident airplane had an errant AOA sensor signal feeding MCAS for the accident flight and the...
Showing results 1 to 25 of 384
 


 
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