This is a translation of the original russian article
Please accept my sincere congratulations.
Good work – right in time for the New Year’s Eve!
Many thanks for your congratulations.
However, the main creators were not us, but the team of young guys - riveters of KnAAZ s . Thanks to their well-planned and dedicated work, we managed to stick to the original schedule "up to the minute". We even managed to compensate for the two "knocked out" days of the Christmas break (when the international airport was not working and even passenger flights were not dispatched) .
And they did their job with the highest quality - just excellent.
Obviously our biggest concern was the rear baggage compartment door (BCD). As it can be seen from the photos with 005 arriving home – the fuselage section F4 has got its bottom panel completely replaced together with stringers and lower arches of the frames, while we had to stitch the door frame from two halves — the upper part of the frame is original, and the bottom half built from scratch. There are double-curvature surfaces there; in addition it was necessary to accurately set door-stops and locks on the newly installed door's longitudinal beam. It was critical to couple and adjust it all precisely to achieve the required cabin airtightness, all what we have done could have been thrown away otherwise. Taking into account that all work was carried out “in the field” – where proper stock and other factory equipment is not available, our colleagues had to develop a few custom tools and equipment units beforehand.
The outcome: the whole "geometry" was ideally restored and it took us just half an hour to manually install the door – it had perfectly matched its opening as well as the fuselage contour.
It took several more days to adjust locks, stops, the depressurisation unit and all other mechanization of the BCD, but … verification of the ECS (environmental control system) during the engine run-ups and initial flyby showed that the airtightness of the fuselage (the time of pressurization and pressure drop) fully matched the specifications, it is not worse than on any serial plane. Plus, we managed to assemble the whole interior of the rear baggage compartment. So she was flying home at FL390 with the baggage compartment filled “up to the top” – there were not just the ZIP and local network cables (were stored in Keflavik since tests in June) but also all tools and equipment used during the repairs.
Finally we were back home just in time and brought back all our stuff. :)
… Between two options […] "capital" repair […] and flying without attracting attention […] well, I mean, "without being ashamed" […] using the regular profile […] the SECOND was chosen as we can see… My “colleagues from Kiev " is also humorously responded to this accomplishment, because the damaged An-70 has been restored quicker (in 4 months) despite the more severe damage…
prototype wrote :
It’s not quite fair to compare the recovery at the Omsk aircraft factory with the recovery in an unheated hangar at a conventional airport and blame the second thing because it lasted longer. In addition the recovery itself took 1.5 months.
Leutenant – there is no need for conspiracy theories, everything is much easier and the matter is not in the "attention attracting profile". The second option was chosen for reasonable and logical explanation: the hangar in Ramenskoye is actively used for its primary purpose. Long-term parking and repair of the 95005 in there would have complicated the work on serial planes… that's all. That's why the decision was made to work “in field" :)
As for the "humour from Kiev colleagues" – haven't they told you by any chance, what resources Omsk and Kiev plants and Antonov Design Bureau threw at the time to recovery of the An-70 after such a serious damage? A giant work, I think, was executed, and I suspect that almost the whole factory was intensively working on this for 4 months. I am really interested to know how many man hours (and $$) has been spent to restore the machine to flying condition in Omsk, and then, after the flight to Kiev …
As for the repair of "five" (95005) , if we exclude the design documentation and production of the custom tools, which was done beforehand, the fuselage repair itself was performed by a single but very capable crew from KnAAZ:
Young guys in the picture — the whole riveters team, girl in the front row performs sealing, a big man standing to the left – a foreman, and the man on the right — technologist. By the way, the both have a maintenance background, so they were not only “inspiring” the team and solving the logistics issues but also actively drilled, riveted, sharpened, sawed , etc. In addition, there were two airframe constructors (were working in shifts changing each other), and a structural expert from the Design Bureau:
It is impossible to foresee all details and some changes in the design and repair process were made "in place". As the result, this little team has completed all fuselage repairs exactly in one month. At the end another crew arrived from Flight Test Facility to adjust the BCD, perform system checks and tests, engine run-ups, test flights and finally to bring the plane home. It all together took just one more week. That's all… And the guys did their work in a temporary tent erected in the hangar, similar to our greenhouses, portable lights and heaters were used (there was ice on the floor of the rest of the hangar).
BTW, it only confirms the fact known by designers — the strongest element of the airframe is the wing caisson. For a lower wing aircraft it takes the main part of the "work" during the belly landing. If it survived such a landing, it can protect the fuselage, even if the plane is dragged a couple of hundred metres along the solid rocks.
16 Jan 2014 00:00
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