777 Tail strike...Hkg

[UpperDeck]

Monday afternoon upon landing. Tuesday departure cancelled. Unworthy of comment?

[Guest]

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ASN Wikibase Occurrence # 219351

Last updated: 12 December 2018

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Date:	11-DEC-2018
Time:	14:54 LT
Type:	Boeing 777-333ER
Owner/operator:	Air Canada
Registration:	C-FITW
C/n / msn:	35298/638
Fatalities:	Fatalities: 0 / Occupants:
Other fatalities:	0
Aircraft damage:	Minor
Location:	Hong Kong-Chek Lap Kok International Airport (HKG/VHHH) -   Hong Kong
Phase:	Landing
Nature:	International Scheduled Passenger
Departure airport:	Toronto-Pearson International Airport, ON (YYZ/CYYZ)
Destination airport:	Hong Kong-Chek Lap Kok International Airport (HKG/VHHH)

Narrative:
Air Canada flight AC15, a Boeing 777-300ER, suffered a tailstrike while landing on runway 07R at Hong Kong-Chek Lap Kok International Airport. The aircraft was able to taxi to the gate normally. The return flight was cancelled, as the aircraft sustained scrape damage to the underside of the rear fuselage.

Weather reported about the incident time (06:54Z)
VHHH 110700Z 33016KT 9999 FEW040 18/10 Q1020 NOSIG
VHHH 110630Z 33012KT 9999 FEW040 18/10 Q1020 NOSIG

[Guest]

Air Canada 777 Tail Hit the Runway Upon Landing — Is That a Big Deal?

by  Jessica Puckett

7 hours ago 

While landing at Hong Kong International Airport (HKG) Monday afternoon, Air Canada Flight 15’s tail struck the runway.

The Boeing 777-300’s tail was damaged significantly — enough that the outgoing flight to Toronto was canceled because the aircraft had to undergo repairs. Fortunately, no injuries were reported.

 

Air Canada did not return requests for comment by time of publication. But, reports say that the pilot at the helm of the 777 said “right on landing… we ended up with a tail strike.” This is actually often the case with similar incidents, dubbed tail strikes.

“Landing is a more difficult maneuver and suffers the most strikes,” aviation expert and former Boeing engineer Peter Lemme said in an email to TPG. Tail strikes don’t occur all too often, but when they do, they are usually minor incidents that cause routine maintenance repairs to the bottom of the plane’s tail. Even if the pictures appear dramatic.

“A tail strike is a symptom of the pilot struggling to control the airplane. However, the outcome is usually just damage to the airplane,” Lemme said, noting that last fatal tail strike was on a DC-8 freight plane in 1995. “The three crew perished trying to takeoff. The tail strike was a symptom of problems, not the cause of the catastrophe.”

In the past decade (excluding Monday’s incident), there have been 38 air transport airplane tail strikes, according to Lemme. In that time period, two 777s had tail strikes in botched landings, with the last incident happening in 2012. During the same 10-year timeframe, Boeing 737-800s and -900s have had seven tail strikes, with the majority of those happening upon landing as well. (Interestingly, Lemme points out that all other variants of the 737 have had just two tail strikes in all of history).

The Airbus A320/321 has had the most tail strikes, recording 14 of them in the past 10 years.

Stretching an aircraft, or making plane models longer, creates greater tail strike issues, Lemme said.

Bad weather can also play a role in creating poor conditions that cause a tail strike. But luckily, many aircraft have equipment to protect against potential damage incurred by striking the runway. “Many airplanes have a skid to minimize damage and to alert the pilot to the occurrence,” Lemme said. “It is possible to that a strike could damage the pressure vessel, so inspection is critical, and any subsequent flying may be limited to low altitude until inspected and cleared.”

The flight crew operations manual for the Boeing 737-800 details what the protective skid on the bottom of the aircraft looks like. It is surrounded by a cartridge that “consists of a crushable honeycomb material,” the manual says. “When the tail skid strikes the runway, the skid moves upward and the honeycomb material crushes.” There is also a device on the plane’s tail called a shoe that contacts the runway if an over-rotation occurs.

Image from 737-800 flight crew operations manual.

For the most part, tail strikes are not serious enough to worry to about. Lemme even experienced one, and the plane’s crew wasn’t sure if the tail had truly struck the runway or not.

“I was on a Boeing 757 test flight that scraped the tail on landing,” Lemme said. “The spoiler settings were being developed, and this time they inappropriately caused a significant pitch up. The flight crew were not sure of contact, but those of us in the back were certain. We flew back to Seattle at low altitude.”

It looks like the Air Canada 777-300 will need to be repaired, but it likely will be back in the sky in no time.

 

[blues deville]

Too bad. Completely preventable however 07R/25L at HKG can be nasty with the reported NW winds. Also perhaps the worst runway surface in use. Should be closed and re-paved.

The scrape looks pretty flat but the serious issue would be potential damage to the pressure bulkhead. However, if you’re going to break your 777 HKG has a world class heavy maintenance base and that tail has probably already spent some time there. 

[Kip Powick]

Rather ironic, considering the aircraft's  registration.

[ILB]

Now rated by TSB as an accident due hard landing according to AvHerald. http://avherald.com/h?article=4c17ab7d&opt=0

[Canoehead]

Definitely more than a scrape... there’s a hole through the structure as a result of a hard landing.  I have heard the number (of G’s) and suffice it to say, I’m fairly certain it’s going to need that heavy maintenance facility for the work likely required.

At least we shouldn’t have to wait 4 years for the report as the TSB has nothing to do with it.

[blues deville]

14 hours ago, Canoehead said:

Definitely more than a scrape... there’s a hole through the structure as a result of a hard landing.  I have heard the number (of G’s) and suffice it to say, I’m fairly certain it’s going to need that heavy maintenance facility for the work likely required.

At least we shouldn’t have to wait 4 years for the report as the TSB has nothing to do with it.

It looks pretty serious to me but not according to the former Boeing employee in the above posts.

His words “It looks like the Air Canada 777-300 will need to be repaired, but it likely will be back in the sky in no time”. 

I don’t think so unfortunately. 

Other photos of the aircraft show it does have a tail skid (newer 777 versions have a tail strike avoidance system) but somehow the crew found a landing attitude/gear extension combo that missed it completely. The -300ER has a max NU of 8 degrees for landing with MLG compressed and 10 when extended. Not a huge margin for error but a good PM can save the day if the warning call is made in time. 

 

[st27]

At what nose up attitude would you have to attain to scrape the tail? It would have to be approaching 8-9*, which would be quite dramatic imo.

[blues deville]

-300ER is 8 degrees which is well above the FCTM 4-5 degree nose up at touch down. Without proper control column input at T/D the aircraft can porpoise or pitch up quickly as the ground spoilers deploy and change the airflow over the elevators. 

[DEFCON]

Did the skid make contact at all?

It looks like the aircraft may have been at a shallow attitude, but dropped vertically, which compressed the struts and allowed that part of the lower fuselage to contact the ground?

 

[blues deville]

2 hours ago, DEFCON said:

Did the skid make contact at all?

It looks like the aircraft may have been at a shallow attitude, but dropped vertically, which compressed the struts and allowed that part of the lower fuselage to contact the ground?

 

I have no idea however it may have made minimal contact with the skid and it saved the fuselage from more severe damage which is its function.

I’d be curious to know if combined with their actual weather was the rough runway surface was a factor? From my experience the north parallel at HKG is used for arrivals (pretty smooth) and the south is departures. Departing on 07R/35L literally beats the crap out of the nose wheel but no one seems to ever complain about a “rough” takeoff.

[DEFCON]

Consider the location of the landing gear, the most forward point of impact damage, the position of the tail skid, the geometry of the fuselage keel between the latter two points and their respective angular relationships to the runway surface..

It would seem that the most forward damage could only be imparted if there was a significant vertical component to the touchdown?

 

[blues deville]

Interesting Defcon. This is an unusual event for this airplane and one of the reasons I’m posting on this thread. 

The 777 MLG is an amazing design (built in Canada) with both the -200 and Freighter series having the standard trailing set of wheels that moves laterally for ground taxi ops. The -300ER series also has what is called a Semi-levered gear where the trailing set of wheels also moves verticality for take off and landing due to the longer fuselage. This was not on the original -300’s so take off pitch was closely monitored and restrictive on that model.  

From Boeing: The Boeing 777-300ER's semi-levered landing gear system allows the airplane to rotate early by shifting the center of rotation from the main axle to aft axle of the three-axle landing gear truck. As the airplane rotates, the nose is allowed to rise higher earlier.

The gear feature is independent of the Tail-Strike Protection system, but provides the ability to take off on shorter runways or put more payload on the airplane for the same length of runway.

 

[Kip Powick]

Great video..Thx for posting...

[Moon The Loon]

The pix above of the damage doesn't show the skid/bumper. From the geometry of the pic posted by Blues D, the skid/bumper should have prevented a fuselage strike.

Tail strikes like this typically occur on landing when flare speed is too low (5 or more < Vref). The resultant pitch on touch down is nose up and. yadda yadda yadda...

Will be interesting to see final report.

[blues deville]

Moon if you sort through all the photos you will see it does have a tail skid. I didn’t see it at first either. 

 

[Canoehead]

 

 

On 12/14/2018 at 11:43 PM, DEFCON said:

Consider the location of the landing gear, the most forward point of impact damage, the position of the tail skid, the geometry of the fuselage keel between the latter two points and their respective angular relationships to the runway surface..

It would seem that the most forward damage could only be imparted if there was a significant vertical component to the touchdown?

 

If the G factor achieved at touchdown (that I heard) is correct, it will explain a lot.  More than just a tail-scrape involved.

[Moon The Loon]

7 hours ago, blues deville said:

Moon if you sort through all the photos you will see it does have a tail skid. I didn’t see it at first either. 

 

Hi Blues: I was referring to the other close up pix of the damaged fuselage, well ahead of the skid/bumper:

[blues deville]

Oh.....roger that Moon.

 

[conehead]

11 hours ago, Canoehead said:

 

 

If the G factor achieved at touchdown (that I heard) is correct, it will explain a lot.  More than just a tail-scrape involved.

So.... what’s the “G” number rumour floating about?

[rudder]

A max oleo compression landing (leading to a possible tail strike) would likely only result from a no-flare/late flare touchdown or a low energy/high pitch attitude touchdown. The common element would be a high rate of vertical speed on touchdown. Wind shear could trigger such an event if an increasing thrust recovery is not initiated in a timely fashion. Reliance on auto thrust could delay such action.

Will be interesting to see if DFDR data is released.

[boestar]

if there is a large G load on landing as is implied above then there is more than just geometry at play.  The fuselage will flex to a point where the belly skin (seen above) will impact the ground before the tail skid.  This can cause excessive stress on the airframe especially at the production breaks in the fuselage.

if the implication is that an actual "Heavy" landing took place in excess of 4 G then there will be extensive NDT requirements on the airframe before being returned to service.  Possibly some hefty repairs as well.

 

[blues deville]

Windshear approaches NRT 16R. Some interesting results.

 

[Kip Powick]

I find it hard to get my mind around the fact that if it was a tail strike, how did the fuselage get scraped so far ahead of the skid ??

Why was there no photos of where there was impact on the runway, surely there would be a paint smudge on the runway but no forum mentions that anything was found on the runway.

Is it possible that the aircraft fuselage touched something on approach prior to landing??

Going to be an interesting investigation/conclusion.....