Tang Guozheng arrived at the scene a little later, but the rain was getting heavier.
In order to ensure the integrity of the site as much as possible, the station urgently set up a huge rain shelter that could cover the Y-8. This move left a very important evidence on the site.
Li Zhan found that the wings had obvious icy phenomenon, and the flaps were malfunctioning due to icy. This was exactly consistent with his previous judgment. After carefully checking the appearance of the fuselage, Li Zhan was surprised to find the crew.
The personnel and millions of goods were just a little short of the time and they stepped into the gates of hell.
According to his understanding of the Y-8, the icy phenomenon on the wings means that the plane will crash at any time, perhaps the next second. The successful emergency landing of the 8y1771 cargo flight is simply the favor of the God of Destiny.
"What did you see?" Tang Guozheng strode and asked Li Zhan standing on the wing.
Li Zhan pointed to the wings under his feet and said, "There is obvious icy, and they walked away at the gates of hell."
"Frozen?" Tang Guozheng subconsciously looked out. The temperature rose after the snow stopped. At this time, the temperature must be above zero degrees, but the temperature in the medium and high altitude areas is not that true, but the icing phenomenon is not easy to explain.
Li Zhan jumped down and clapped his hands and said, "I asked the unit that the deicing system is turned on. However, the deicing system of the Y-8 relies on the engine heat to work. After the two engines no longer provide thrust
It has affected the working effect of the deicing system, and it is basically certain that this is the reason that the flaps are frozen."
Zhang Wei added, "Frozen wings will affect air flow, and the consequences will not be much better than the flap being frozen."
The pilot is naturally very clear about the consequences of the wing freezing, and senior pilots know the power of it. The wing is the main component that provides lift. The air flows smoothly from the upper and lower part of the wing to generate lift or downward pressure, driving the aircraft to rise or fall
Once the smooth flowing air is changed, the wings cannot provide sufficient lift or downward pressure normally, and the aircraft will rise or fall uncontrollably, and the final result is a stall crash.
The consequences of the flap being frozen are obvious - the pilot cannot control the aircraft to rise or land normally. The crew of the 8y1771 cargo flight should be glad that it is in the maximum lift position before the flap is frozen, that is, the take-off and landing position, otherwise
They simply cannot support the Zhongnan Station, which is within reach.
Tang Guozheng asked Li Zhan curiously, "Do you know Yunba very well?"
"I know better than other aircraft." Li Zhan smiled and pointed to the exhausted Yun-8f-400, and said, "I am very familiar with each model of Yun-8, and I will say that some models are not exaggerated.
You can even disassemble and assemble with your eyes closed."
Tang Guozheng asked, "How come you are so familiar with Yunba?"
Li Zhan shook his head slightly and said, "You can't say it."
After a little surprised, Tang Guozheng no longer talked about this topic, and Zhang Wei felt even more strange. Li Zhan had never contacted the Y-8 in the second division for nine months, and it should be said that except for the J-7e
He has never had any contact with the rest of the J-7 aircraft. Did Li Zhan come into contact with these aircraft while working in Beiku?
Tang Guozheng looked at the plane, his eyes fell on the blackened engine, frowned and said, "What do you think is the reason for the engine catching fire?"
They treated this civilian Y-8, numbered b-25277, as an aircraft of the army, and regarded the current accident as an accident of the army, so they discussed it very seriously. Li Zhan even regarded the accident as a result of the accident.
Make a rare practical opportunity and use his strengths to do some very useful research and analysis.
Li Zhan said, "It should be caused by hot start. The fuel supply system did not stop after the two engines stopped working. The unit cut off the fuel supply when the engine restarted according to the procedure, but at this time there was already a lot of fuel in the engine, so
The fire broke out after starting the engine with the apu.”
After a pause, he said, "The engine fire is not the most dangerous situation. I think icing is the main reason why the plane has to land forcibly. The crew has cut off the fuel supply of the fire engine in time. It was raining heavily and the fire in the engine compartment was in full swing.
It will not develop very much in any case, but will gradually weaken. However, the crew did not realize that the two engines lost their function and affected the normal operation of the deicing system, and the wings and flaps began to freeze. They thought the flaps
The loss of function was that the fire in the engine compartment spread to the wings. In fact, it was not. The fire was not very big at that time."
"Have the cabin sound recorder and the flying ginseng recorder been removed?" Tang Guozheng asked along the way.
Li Zhan said, "No need to dismantle it, just extract it."
Zhang Wei reminded, "Chief of Staff, Captain Li, this is not our plane."
The two were stunned and their emotions stopped abruptly. Li Zhan smiled awkwardly, "Oh yes, it's not our plane, the investigation should be the responsibility of the Civil Aviation Administration. Yes, I can provide them with some help to complete the investigation as soon as possible and remove the plane as soon as possible.
”
"It should be no problem. They may wish us help." Tang Guozheng said, "We can learn from it as well."
Li Zhan said, "Without the weather not changing significantly, the Chief of Staff sent a few people to me. I immediately started a preliminary investigation and some evidence should be fixed."
"I will send someone to you, but to launch an investigation, you must obtain the consent of the Civil Aviation Administration. This way, you can continue the investigation without affecting the situation on the scene. I will ask my superiors for instructions immediately." Tang Guozheng said decisively.
"yes!"
Zhang Wei asked the people at the station to find a SLR and took photos of some parts of the plane according to Li Zhan's instructions, especially several areas that had not yet melted. There was no news on Tang Guozheng, but Li Zhan's side
But I have obtained more and more information.
Li Zhan’s familiarity with the Y-8 series medium-sized transport aircraft is beyond the ordinary people’s imagination. He has really had several experiences in disassembling and assembling this type of aircraft with the crew. With the help of several necessary auxiliary equipment, he relies on the tools in his hand.
They were able to basically break down the early models of the Y-8 in an hour.
The Army's big head soldiers played the decomposition and combination of light weapons, while Li Zhan and others played the decomposition and combination of aircraft. In order to make the pilots' understanding of the aircraft they mastered reached the extreme, Liu Guojian asked every pilot to complete three times within one hour.
Decompose the aircraft test and one assembly test.
Therefore, Li Zhan is very familiar with every part on the Yun-8, just like familiar with his own body parts.
The subsequent large number of modifications are inseparable from the essence. When the modification was shipped to the -8, Li Zhan and others were exposed to the subsequent models and were very clear about the situation inside.
Li Zhan knew very well that one of the major shortcomings of the Y-8 series aircraft is that the de-icing and anti-freeze system is not easy to use, and has not been completely solved so far. In order to prevent accidents due to icing, a large number of Y-8s were required to be restricted to the south of the Huaihe River.
When used, plateau areas are basically not used.
By calculating the meteorological conditions and flight parameters, load capacity, unpowered gliding distance and other data in the airspace where 8y1771 is located on that day, Li Zhan suddenly found that even if there were only two engines left on the flight, he could fully glide to the tourist airport, provided that the deicing system was turned off.
.
The engine power occupied by the deicing system has become the biggest obstacle to limiting the arrival of the tourist airport. Of course, if the deicing system is not turned on, the 8y1771 may not even be able to reach the Zhongnan Station.
However, this discovery is of great significance and can provide useful reference for manufacturers to improve the machine's deicing system. The weather encountered by 8y1771 is very representative. In subsequent large-scale surveys, it was found that the same weather often occurs in the Central and Southern regions.
But there has never been a Y-8.
More and more questions have been found, but what caused the engine to stop was the last question without clue. The investigation team of the State Administration of Civil Aviation has done a lot of directions with the assistance of the army investigation team led by Li Zhan.
According to analysis, several possibilities have been ruled out.
As New Year's Day in 2012 approaches, Li Zhan raises a possibility - will the question also lie in the deicing system?
This is a known system with congenital defects, and generally there will be no problems. However, when encountering weather encountered in 8y1771, defects in the deicing system will definitely be exposed.
But is there a relationship between the deicing system and the engines No. 1 and No. 2?
Li Zhan told the Civil Aviation Investigation Team that the power system used by the Y-8f-400, which uses the turboprop-6 aircraft engine as the main component, has a device to prevent excessive power. If the crew does not lift the restrictions, then the engine power exceeds the rated value.
The rear limiting device will intervene and force the engine power to decrease. If this phenomenon continues, in order to prevent the engine from failing in overload operation, the limiting device will intervene. In this case of constant intervention, the engine may be shut down.
When the deicing system senses that the icing phenomenon still exists, it will always ask for energy from the engine, occupying more and more power of the engine, which is completely possible to cause the engine to operate overload.
The deicing system and the engine protection limiting device are not smart enough, and are straightforward and reckless. Unless the pilot intervenes in adjusting their relationship, they will always be in a tug of war. The deicing system constantly asks for more power, while the engine protection limiting device is born.
It grabbed the engine speed to avoid overload.
To verify that Li Zhan's analysis, the actual aircraft experiment must be carried out. The investigation team asked the troops for assistance. The flight test institute located in the Aircraft City accepted the task. After several days of experiment, the results were transmitted to the Zhongnan Station. After seeing the conclusions, the investigation team saw the conclusions.
He was shocked - it was exactly consistent with Li Zhan's analysis.
No one expected that the interaction between the engine limiter, which was originally an aircraft protection device, and the deicing system, would almost kill the plane.
The investigation conclusion of the accident attracted the attention of the airline and the manufacturer. A higher-level investigation team went to the Central South Station before New Year's Day to learn more about the situation. The detailed report of the military and local investigation team's elimination allowed the high-level investigation team to be so
After obtaining the treasure, the solution direction and methods of some problems encountered in the development of the Yun-X tactical transport aircraft were basically determined.
The remaining problem for Li Zhan is how to get the b-25277 away, and his next exploratory flight would not be carried out without getting the plane away.
The joint military and local investigation team came to the scene to discuss the plan.
Plan 1: Dismantle and transport it away. Plan 2: Use a heavy helicopter to lift it away.
The cargo has been cleared long ago, both methods are feasible, but the plan will cause difficult damage to the aircraft, because it is difficult to pass through the over-spec flatbed vehicle on the way down the mountain, and the body must be divided, so the aircraft cannot continue.
When used, you can only remove the useful parts and use them as aviation materials and use them into the furnace.
Solution 2 requires the use of the world's largest helicopter, Mi-26. Only this helicopter can lift the body of the Yun-8g-400. However, the wings still need to be removed to reduce weight so that they reach the allowable loading weight range of Mi-26.
Within. And this method is very dangerous.
Everyone was discussing in a panic. On one hand, the troops continued to clear the runway and resume normal work. On the other hand, Post Airlines also hoped that the plane could enter the repair shop as soon as possible and put it into operation. The loss of the plane was hundreds of thousands of dollars a day after the plane was grounded. Post Airlines was home again.
Even if you have great achievements and great achievements, you will not ignore such huge losses.
However, Li Zhan walked to the front of the front of the plane and squatted down, facing the entire plane lying on the runway, dazed.
Tang Guozheng and Zhang Wei continued to discuss with people from civil aviation, airlines and insurance companies, and their opinions gradually tended to remove large parts with larger weights such as left and right wings, vertical tails, horizontal wings and landing gears, and then use rice-
26. Carry away.
Zhang Wei discovered Li Zhan’s abnormality and walked over, squatted down and looked at the plane in Li Zhan’s eyes, "What are you thinking? Your opinions are almost unified, and you can use the second solution."
Li Zhan seemed to have not heard Zhang Wei's words and said to himself, "The aircraft has no structural damage, and the frictional damage on the belly should not have a big impact. The engine fire did not burn the wings, and the landing gear may not have
It is severely damaged. It should be OK to replace the two damaged engines and help the plane up and drive away."
"Drive away?" It took Zhang Wei a long time to come to his senses, his eyes were about to pop out, "Drive away? Are you saying that you can fly away directly?"
Li Zhan was still thinking hard, as if he was calculating something.
Zhang Wei did not dare to disturb Li Zhan, so he held his breath and waited for Li Zhan's answer.
Suddenly, Li Zhan stood up and raised his hand and said loudly, "Plan 3! Get out! The plane can fly away directly!"
The members of the military and local investigation team surrounded the nose of the right side of the plane looked over at the same time.
Someone said, "Flying away? I'm dreaming in broad daylight."
However, after surprise, more people fell into deep thought and reexamined the b25277 on the ground again - the plane seemed to have no other major damage except for the damage of two engines.
More and more people fell into deep thought, and then they thought about it. When several technicians quickly walked around the plane to observe, almost everyone's eyes lit up.
They realized that this might be the perfect way.
ps: I have to check the Air Crash Day before going to bed these days...