Jet brought back from deep sleep
Two years since ZK-OKO was grounded, it’s just weeks away from taking to the skies again. Just like four Boeing 777-300ERs Air New Zealand has parked up in the Californian desert, the big jet idled at Auckland is being brought back to life to meet the torrent of demand for travel.
While engineers working on the planes in the Mojave Desert boneyard face the threat of rattlesnakes and scorpions, those working in Auckland have encountered far more friendly wildlife. They found nesting birds at the top of the 18m high tail of the plane. But all aircraft must go through a process of being “preserved” and “de-preserved” or “reanimated” following a detailed checklist set out in chapter 10 of Boeing’s 777 aircraft maintenance manual.
The aircraft in Auckland was one of three 777-300s kept in the city rather than flown to the boneyard at Victorville, where Air New Zealand and other airlines stored hundreds of planes during the pandemic in a very low humidity environment. The airline’s eight 777-200s were also parked at Auckland before being flown to Roswell in New Mexico. Those planes are older and smaller than the 300s and won’t be returning to the fleet.
Since its last flight from Los Angeles on August 24, 2020, ZK-OKO has been in long-term preservation in Auckland. It will be the last of the three stored here to re-enter service. The plane carried loads of up to 342 passengers to destinations such as London and Los Angeles for years until Covid-19 hit.
The key reason the three 777s were kept in Auckland rather than flown to California was for them to undergo major undercarriage work, scheduled every 10 years in a hangar and taking hundreds of staff hours. The planes in Auckland were initially put into active storage — a six-month programme of intense maintenance — but then as it became clear the pandemic would impact air travel for longer, that became long-term storage. Air New Zealand added tweaks to the manual to match the unique weather in this country and some operational requirements.
After consulting Boeing, instead of draining fuel tanks dry, 30 tonnes of fuel was left in them. Even though the aircraft weigh close to 160 tonnes when empty, the extra weight of fuel prevented them from being blown about. And unlike others in the desert, the plane has had its auxiliary power unit (APU) on once every four days to keep some systems running, including its air conditioning to keep its cabin at the required humidity levels — below 70 per cent — to prevent damage to seats and other parts of the interior.
But outside Auckland’s humidity caused corrosion in four GE90 engines on the planes and earlier this year the airline said they would need repairs overseas. They were sent to MTU Aero Engines in Munich for work and the final one is being fitted to the left-hand side of ZK-OKO this week.
When the pandemic hit, the work to preserve the planes was frantic. Working through Boeing’s preservation checklist for the 777-300s takes about 400 to 500 staff hours.
Windows were sealed with tape, and pitot tubes used to measure air flow were sealed (as they are for shorter periods when planes are grounded). Also sealed were static ports on the tail, used to measure the yaw of the aircraft. Wheels and engines were wrapped and a green anti-corrosive coating applied to metal leading edge surfaces on wings to protect them.
The APU was not only used for a blast of air conditioning in Auckland but also to make power available to flight deck for restarting systems. In the desert, aircraft were in a deeper sleep with equipment such as circuit breakers removed from the flight deck.
Engineer Gary Bennett is an Air New Zealand production planner and a leader of the team which has done the work in Auckland and said that once in storage planes were subject to checks at regular intervals ranging from weekly to once a year. Every 30 days the planes were moved to even out pressure on tyres and every 90 days the planes were brought into the hangar for where lubricants were refreshed and parts of the plane serviced.
Fine metal parts such as lightning conductors have needed extra attention because of the effects of weather but otherwise engineers have found the planes in Auckland in very good condition.
Besides major undercarriage work, there’s been some re-configuration within the cabin.
Although the number of seats stays the same, some will have extra legroom, and some won’t.
Emergency slides have also undergone scheduled maintenance.
Technical staff from Panasonic have been working on inflight entertainment systems which will be loaded with new content.
The grounded planes have also provided an ideal environment for new cabin crew or those who have undergone refresher training for 777s.
In total, the planes in Auckland have had about 4000 to 5000 hours of work on them to reanimate and do the heavy scheduled work and preparing cabins. Those planes at Victorville will be reanimated for flight in accordance with requirements from regulators and Boeing, but the extra work will be done back in Auckland.
For ZK-OKO, August 19 is a key date.
That’s when pilots will work through four to five hours of checks — operating a virtual flight on the ground.
Four days later they will do the short verification flight required after both engines have been off the and the plane has been idle for so long.
All going well, it will then re-enter service with passenger flights.