Virgin Aircraft pod strike 737 Samoa

[blackbook]

https://www.atsb.gov.au/publications/investigation_reports/2016/aair/ao-2016-042/

[Ken Borough]

A pod strike on the 23rd but not detected until the 26th after review of flight data recorder. Would one expect that to be the norm?

[blackbook]

No not the norm preflt inspections done properly should pick up any strike damage to the lower surface of the engine.

[The Green Goblin]

A stab almost torn off and continued flight with pax.

A pod struck and continued flight....

Something stinks over there. JB better get some better oversight. It wouldn't be nice to be the first Australian passenger jet operator to lose one.

Poor cash flow, high levels of debt, a shrinking network, poor maintenance oversight and splashing out on sponsorship deals? I think we've been here before. With the same players too.

No wonder the kiwis are bailing.

[framer]

When I check under the engines during my walk around I look at the different latch locations. I am not sure if I would pick up a scratch on the paintwork if it was between the latch locations. ( after reading this I probably will!)

[Mr.Buzzy]

You're kidding yourselves if you think you're going to reliably see anything other than proud cowl latches on a typical 737 walk.

[neville_nobody]

No not the norm preflt inspections done properly should pick up any strike damage to the lower surface of the engine.

And when was the last time you saw a 737 pilot on his hands and knees looking under the engine during a walkaround?

[No Idea Either]

Perhaps the crew who were operating at the time should have been aware that something was possibly amiss after the arrival and had a better look after shutdown. Not speaking up out of fear or ridicule risks all the lives of everyone who operates and rides in that machine afterwards, until it's detected. No wants to scrape a pod, it was a genuine mistake and should be owned up to. I believe that the 'just cause' accountability protects you and when it all boils down, apart from the mishap, it's just good airmanship and integrity to own up. Keg said in another thread that we should all be looking after each other, regardless, this is just another example.

[Oakape]

On my last walk around I spent a few minutes on the issue. The only way I could see well enough under the pod to identify damage was to get on my hands & knees. And I had to do it on both sides of the engine to cover the area completely. Not exactly practical on dirty tarmacs & in the rain, snow & ice. I guess the only other way is to lie on your back & slide under. Like you are going to do that in uniform. Either way, I don't think there is a practical way to adequately inspect the area on a walk around.


Management don't care. They just put in the manual the requirement for the pilot doing the walk around to check the cowl latches & to check for damage under the pod & provide no instruction on how to achieve that. Then they hang you for not doing so when damage goes unnoticed.


The FCTM chart shows that the flap track fairing will hit before the nacelle at pitch attitudes above 1 degree. As there is no reported flap track fairing damage, one would have to assume that the pitch attitude at touchdown was 1 degree or less. That is an awfully flat touchdown attitude. One has to think power into the flare, downslope on runway, float, push it on. Time will tell.

[Checklist Charlie]

Oakape, that's all very well and good for pitch but what about a strike due to roll?

CC

[Oakape]

The chart gives nacelle contact with roll from 11 degrees through to 17 degrees. So -4 degrees pitch combined with 11 degrees roll, through to +1 degree pitch combined with 17 degrees roll. This is first point of contact & the pod may have hit after the nose wheel at low pitch attitudes, but at the higher pitch attitudes the flap track fairing will hit before the pod. In fact, if the flap track fairing hits, I would be surprised if there was also a pod strike. For that to happen, there would have to be a marked decrease in pitch without any reduction in roll, unless you just happened to be right in that corner of the envelope. There had to be roll in there, but I believe the pitch also had to be very low. I have noticed a tendency over the years for 737 pilots to carry the power into the flare which leads to very flat landings - almost 3 pointers, particularly at flap 40. This may be part of the problem. Also, Boeing states that contact can occur inside the envelope due to structural flexing of the airframe. This may have been a factor here.


The wind was from the right & was gusty. Viz was reduced in heavy rain & it was at night. Remember that the cyclone was passing at that time. Depth perception can be difficult in rain on that runway at night. The runway edge lights for the first 1/4 or so of the runway are much brighter than the rest of the runway & this makes it more difficult to see & use the full runway for depth perception when the viz is bad. The runway is quite long, but is ungrooved & has a downslope. So there is some extra urgency to get the aircraft on the runway & stopped when there is heavy rain.

[Gate_15L]

Oakape, nicely put.

[Snakecharma]

There is quite a dip in the middle if I recall correctly, leading to the illusion that the runway is falling away then rising up to meet you.

I have not been there for years now, but when I was operating into there there was bugger all ambient lighting so it is a bit of a black hole approach just to ratchet up the difficulty level in crappy weather.

[Ken Borough]

I think the concern of many would be not so much about a pod strike per se but what happened, or didn't happen, thereafter until the strike was identified some days later.

[framer]

Ken, my thoughts are that based on what Oakape says here;

The only way I could see well enough under the pod to identify damage was to get on my hands & knees. And I had to do it on both sides of the engine to cover the area completely.
and the fact that I am quite diligent when inspecting under each engine on my walk arounds yet doubt that I could see a scratch between the latches, that it is very likely that pilots won't pick this up on walk arounds.
I agree that that should not be the case, but believe it is the case at the moment.
I don't have to get onto my knees to check the latches but do get right down on my haunches as low as possible and can identify all the latches from that position.I haven't done a walk around since this thread started but like Oakape will be paying special attention to whether or not I can see the entire surface.

[Gate_15L]

Yeah, after thinking about it, I 'm thinking of getting one of those small inspection mirrors that are on a telescopic rod with a movable mirror.. That pod is very low on the NG... It might work, it might not, but worth a shot... If the toothpaste brigade don't take it off me or some hostie doesnt accuse me of looking up skirts with it... :O

[Snakecharma]

Ken for something to happen post the landing assumes that the crew knew they had scraped the pod.

I don't think it is a given that they knew they had dragged the pod and given it was pissing down and not many people I know do post flight inspections it is not unreasonable that it wasn't immediately reported.

As for the preflight inspections, I think there has been plenty of discussion that indicates the difficulty in identifying the damage given the location so put it all together and the fact that the damage went unidentified for a few days is not surprising.

[BuzzBox]

The crew reported touching down firmly...

Did they suspect a hard landing had occurred at the time? If so, was it reported at the time? Surely that would have warranted a close visual inspection that should have revealed the damage to the pod.

[Snakecharma]

The threshold for triggering a hard landing inspection is quite high in terms of g loading, though in many aeroplanes there are variable g limits based on roll rate etc on touchdown, so very difficult for the crews to identify if the landing they just did was actually a heavy landing.

Most reported hard landings are shown to have not exceeded that threshold, though that is usually after the fact when FOQA data is reviewed. The inspection having been done at the time in order to get the aeroplane moving again.

Again it isn't a huge surprise that a heavy landing report wasn't submitted as it needs to be a real bone crusher to actually be a heavy landing.

I am not privy to the details in this instance, nor trying to defend the actions of any party, just trying to point out that things are not as necessarily cut and dried as perhaps some people may like to believe.

[BuzzBox]

Thanks Snakecharma. We've had several instances of 'firm' landings that weren't reported at the time but were subsequently determined to be 'hard' when the data was analysed. We've had it drummed into us that if there's any doubt it should written up as a hard landing and investigated accordingly. Mind you - I work for a big international airline wih engineering resources at every port, so it's relatively easy to complete the initial inspection of the aircraft. Not sure if the same applies to Virgin's operation at Apia.

[ringbinder]

The aircraft most likely did several sectors over several days after the Apia landing. That would have provided a number of crews and a number of engineers the opportunity to pick up any damage. That they didn't suggests no- one does proper external inspections or that the damage was extremely difficult to detect. My money is on the latter, especially seeing it was only after the engineers were specifically tasked to look for it.

[Snakecharma]

Buzzbox, we are also encouraged to report "just in case" which is why the majority are inspected, investigated then found to be below the threshold.

The unintended consequence of this, particularly for someone who has previously reported a suspected heavy landing which was subsequently found to be below the threshold, is that your expectation shifts. By that I mean you land the aeroplane with a crunch, go "oh crap I had better write that up", they inspect the airframe, look at the FOQA data and the feedback is that the landing was well below the heavy landing threshold. Next time you go crunch you go "yeah that was a thumper but no worse than what I did last time and that one wasn't even close so no need to report it" or words to that effect :)

Nothing sinister but it leaves room for the occasional one that goes the other way and does exceed the limit but isn't reported. Sure some might try and cover it up but in the operation I work for I would think (hope) they are in the minority, with the unreported ones there because the crews genuinely didn't think it was that bad.

[BuzzBox]

Thanks Snakecharma, I understand all that. The Aviation Herald reported that the return flight to Auckland was cancelled and the aircraft ferried back to Auckland the following day. If that's true and the flight cancellation/ferry flight wasn't for some other reason, then it sounds as though the airline suspected something was up. As ringbinder said, perhaps the damage was extremely minor and difficult to detect.

[Oakape]

The reason for the delay, as I understand it, was due to the cyclone. If the 'airline suspected something was up', the aircraft would not have been allowed to fly for 2 further days.


The damage was not minor, in fact it was quite serious. As it was contained to the area around the bottom of the cowl, it was not picked up by all the pilot & engineering inspections after the event. I was told that even the engineers do not look at that part of the airframe when doing daily or EDTO inspections. I was informed that they are only required to ensure that the cowls are latched & squatting to be level with the bottom of the cowl meets that requirement, as latches that aren't fastened will be hanging down.

[BuzzBox]

If the 'airline suspected something was up', the aircraft would not have been allowed to fly for 2 further days.

Well I guess that would depend on the results of a phase I inspection, assuming one was conducted at the time. Still, it sounds as though the crew didn't consider the landing to be 'hard', so didn't report it as such and therefore no inspection was triggered at the time. That didn't occur until later, when the QAR data was analysed as part of the airline's FOQA program.

[Capn Bloggs]

You guys need a pod-scrape indicator, ala tail-touch indicator.

[hoopdreams]

In the part of the world I fly, QAR exceedence parameters are a big deal, hard landings in particular. If a hard landing is suspected we can print the load report which shows the G load at touch down, on the a320, 1.75g is considered a QAR exceedence.

Can the load report be printed on the Boeings, showing such info?

[blackbook]

I have seen some photos. Latches were damaged in the strike, it starts just from the nose cowl all the way back to the reverser latches, with a number of holes through the structure.
As for picking this up on a preflt, if after you have looked at the fan blades you bend over while using the inlet cowl for a hand steady you can bend over far enough without lying on the ground and see all the way back along the engine. This is not the first time for a 737 to have a pod strike. Ryan Air had an identical event on two aircraft 2009 and both were missed by subsequent preflt.
I have watched the preflt being carried out by crew and it varies dramatically. Some walk from the nose around the engine across to the outside of the other engine back again like they are on the modeling cat walk without even looking at the aircraft, obviously thinking more about what's ahead of him or her rather than the importance of the task that he or she are carrying out alone. This task used to be backed up by a ground engineer and this was his sole task and he was equipped for this, no matter what the environment or weather conditions offered. I see crew without raincoats substandard torches (iphone torch) trying to complete a task that is often pushed by time, and sometimes the must get home attitude(defects always logged on the home leg). I see many crew finding themselves in this situation often without any immediate engineering support on hand as a result of a industry wide cost reduction. Two sets of eyes were always better than one. It's a race to the bottom reducing cost, until unfortunately we see a catastrophic incident.

[framer]

Blackbook I think you have gone straight to the heart of it.
In this particular case it is a pod strike, but there are 100 other potential cock-ups that are more likely to sneak through as a result of the constant reductions in systemic safety. Each policy change on its own looks like it can be safely initiated but it feels like we are getting to a point after chip chip chipping away where we are relying on a dose of luck and the pilots to get the aircraft away quickly and safely.
Not only has Engineering support be reduced, time available to sign on and get to the aircraft has remained the same while security takes longer and gates are further from the sign on locations. Add to that the ground staff with a clipboard scribbling down what time crew arrive at the aircraft ( read your 250 notams boys?) and the email you receive telling every company employee that the aircraft was 4 minutes late off blocks due to "Pilots" and the scene is set for people to rush and cut corners.
Not checking the bottom of the cowls is now just ops normal for many in a bid to satisfy folk who would stutter if you asked them to define safety.
Edited to ask: How many of you have gone more than five years without being checked or trained on conducting a walk-around? I have gone seven years now. It must be an unnecessary expense I guess.

[The Green Goblin]

Has Boeing got a prescribed walk around procedure like Airbus?

You just follow the diagram until it's memorised and then a walk around should be performed exactly the same everytime.

I've noticed most of my colleagues follow the same walk around pattern/procedure at my company.

[framer]

Yip. They have a prescribed single engine approach procedure as well. I have also heard that McDonalds have a prescribed procedure for making a cheeseburger and ensure that the procedure is adhered to as it is critical to the safety of their balance sheet :)

[framer]

From the latest version of the FCOM;
the engine inlets and tailpipes are clear, the access panels are secured, the fan cowls are latched, the exterior, including the bottom of the nacelles, is not damaged, and the reversers are stowed

[morno]

We're not flying the space shuttle boys. Nor are we flying the Constellation anymore.

A thorough check by an engineer once a day should be adequate, plus a thorough walk around by a pilot before each leg.

morno

[The Green Goblin]

Obviously we should be treating it a bit more like one. They'll both kill you if you miss something important and they are both mechanical machines hurtling through the atmosphere or above it at a great speed.

They also both have wings :)

[framer]

thorough check by an engineer once a day should be adequate, plus a thorough walk around by a pilot before each leg.
Agreed. I'm not convinced that the pilot walk around is as thorough as it was say ten years ago though.

[The The]

Agreed. I'm not convinced that the pilot walk around is as thorough as it was say ten years ago though.

Maybe, maybe not?

Virgin pilots failed plane-check duties - smh.com.au (http://www.smh.com.au/articles/2003/03/05/1046826438511.html)

[BPA]

Reference the Ryanair pod strike in 2009 mentioned above, here is the report.

http://www.aaiu.ie/sites/default/files/report-attachments/13184-REPORT_2011_007-0.PDF

[Capn Bloggs]

the email you receive telling every company employee that the aircraft was 4 minutes late off blocks due to "Pilots"
Are you serious, Framer??

[framer]

Are you serious, Framer??
Yes unfortunately I am. It's a bit sad really isn't it.

[Pakehaboy]

From the latest version of the FCOM;
That is some funny stuff there framer.I think we've all seen a walk-around or two and observed that they haven't looked at a bloody thing.Out of curiosity,how is a "hard" landing measured?On the Bus,319/320/321,anything over 300fpm requires inspection.I have to correct myself,that's for a overweight landing,but talking to my engineer mate,he says they use the same criteria for a "hard" ldg as well


....by the way the funny stuff I was referring to was the the hamburger post

[Berealgetreal]

http://http://australianaviation.com.au/2016/05/virgin-australia-plans-return-to-vanuatu/

[Ken Borough]

Two and a half years later, there’s still not yet a report of the ATSB investigation. How disgraceful?

[PoppaJo]

I’m still waiting on the report on the more serious, Jetstar/AirAsia near collision above OOL from mid 2016.

2/3 years between final reports is along time that potential bad practices continue on.