V. Answer the following questions using the underlined words in the answers.

1. What may be the reasons of aircraft disintegration while landing?

2. What can lead to skidding off the RW?

3. What altitude is flyby performed at?

4. In what cases do the pilots perform G-load procedure?

5. Is it possible to ditch the aircraft on the sea during night?

6. What human mistakes can result in undershooting of the RW?

7. What can be expected if tire shredded away during landing?

 

VI. Explain the meaning of the phrases.

· Low pass

· G-load procedure

· Ditching

· RW excursion

· Skid off the RW, slide of the RW, veer off the RW

 

VII. Discuss the following questions.

1. What is the purpose of gear system?

2. What technical reasons can result in gear malfunction? How?

3. What human mistakes can cause undercarriage problems? Do you know any examples?

4. Enumerate all possible landing gear problems.

5. What can cause gear problems?

6. What is possible to expect if all gears fail to extend? What preparation should be performed at the airport in this case?

7. What is possible to expect if one of the gears fails to extend?

8. What can be the consequences if nose gear is inoperative?

9. What may be the results if gears can not retract after take off?

10. How dangerous is the situation when the gear is not locked?

11. What may be the results of tire burst? What can it be caused by?

12. What do the controllers have to do in case of gear problems?

13. Have you ever faced with gear problems in your practice?

14. Will you recollect any accident or incident that occurred because of undercarriage malfunction?

 

VIII. Read and discuss the text.

GEAR PROBLEMS

  Undercarriage system plays vital role in providing safe completion of take off and landing. So, any malfunction or deficiency in it can pose risk to structural integrity of the aircraft and thus for its controllability and safety.

The landing gear problems may be caused by variety of reasons:

Technical reasons such as

· Hydraulic system failure

· Electrical system problems

· Tire burst due to

√ overheating (may be because of extremely hot weather with the temperature above 50 degrees; it leads to heating of the concrete and as a result in overheating of tire while rolling at high speed)

√ rough landing

√ overweight landing

√ rejected take off (sharp applying of brakes at high speed can result in tire burst)

· Mechanical failure (the rest of the system may work but the actual mechanism fails to operate due to metal fatigue)

Outside reasons

· Malfunction of gear due to impact with a foreign object on the ground while rolling for take off

· Malfunction of gear due to bird strike

Human factor

· Mistakes of ground personal

· Errors of crew members (there were situations when pilots merely forgot to extend it or their airmanship was not enough to perform smooth landing)

On the 26^th of October in 2009 at Sydney airport pilots of B767 Qantas air company forgot to release the gear. Pilots noticed their mistake when automatic emergency system went off. The aircraft was 700 feet from the ground at that moment. Pilots managed to increase engines power and went around. Investigation revealed that captain and first officer misunderstood who had to perform gear extension procedure.

On the 1^st of October in 2010 at Kaliningrad airport B737 with 138 passengers on the board performed belly landing as the pilots forgot to low down the gear. While approaching to the airport pilots prepared for landing, extended landing gear but soon revealed that flaps were out of order. They went around; they had to retract already extended gear. During second landing approach the crew extended flaps with the help of emergency system and proceeded to landing forgetting about the undercarriage. Only when engines touched the RW pilots realized that they were performing belly landing and they pulled gear lever. Nose gear is usually extended faster that’s why it managed to be lowed down but main ones didn’t. It has just rained and RW was slippery- this fact prevented ignition. Investigation found out that the captain had about 20 flight hours and co-pilot about 60.

 

Consequences:

There are various problems connected with landing gear such as all gears are not extended, all gears are extended but one is not, gear is not retracted, gear is extended but not locked, nose gear is inoperative, tires blew out.

In case landing gear is not retracted crew need to evaluate the situation, take into consideration distance to their destination, recalculate the amount of fuel and if it allows they may proceed to the airport of destination at low altitude or land at the airport of departure.

In case landing gear is not extended an emergency situation has to be considered. Crew surely will apply some attempts to low it down and extend it manually. In case the power system fails, an emergency extension system is always available.

If gears don’t respond to conventional methods, pilots can also apply G-load procedure. They can dive the aircraft in smooth air only to a certain speed and then pull up. It creates G load on the structure and forces the gear to get down and lock.

If they don’t manage they will declare emergency and perform belly landing on grass RW if there is such at the airport, if no - pilots request foam carpet on the concrete RW. Sometimes smooth hard runways are preferable than rough unimproved grass strips.

If one landing gear fails to extend pilot has two options – to land on available gears or with all gears up. Landing on one gear usually poses risk to structural damage of the fuselage and ignition. It veers the aircraft to the side of faulty gear after touch down. Before landing pilots can consume as much as possible fuel from the wing of affected side therefore to reduce weight from this side. It makes it possible to delay an unsupported wing from contacting the surface during landing run until the last moment. But such kind of landing requires great airmanship from the crew.

During a belly landing, there is normally extensive damage to the airplane. Belly landings carry the risk that the aircraft may flip over, disintegrate, or catch fire if it lands too fast or too hard. Strong crosswinds, low visibility, damage to the airplane, or unresponsive instruments or controls greatly increase the danger of performing a belly landing. Still, belly landings are one of the most common types of aircraft accidents, and are normally not fatal if executed carefully.

    Usually the term “belly landing” refers to situation when gear mechanism fails to extend and the term “gear up landing” refers to the situation when pilots forgot to extend gear.

In case landing gear is extended but pilots are not sure it is locked, they will request low pass procedure - circling over the tower or airport at low altitude for ground engineers to observe the position of gear. It should be done in daylight. In case of dense fog this check can be performed in air by another aircraft. The position is reported to the crew and they make decision about further actions.

In case there was rough landing or some debris on the RW it can lead to tire bursting, or tire ignition due to overheating. It in its turn can result in skidding off the RW or sliding of the RW. Aircraft may stuck in the ground and tug may be required.

  ATC has to

· acknowledge the gear problem, ask for the crews’ intentions when the situation permits, and establish whether the crew is able to extend the gear into locked position;

· separate the aircraft from other traffic, prioritize it for landing (allow long final if requested), keep the active runway clear of departures, arrivals and vehicles;

· impose silence if necessary;

· inform the airport emergency services and all concerned parties according to local procedures;

· provide the flight crew experiencing gear problems with any information requested and deemed necessary (e.g. type of approach, runway length and aerodrome details, etc.); in case of a maneuver for gravitational drop, the crew will surely need minimum safety altitude.

· not to press the crew with non urgent matters;

· prepare for LOW PASS for visual inspection (if required); NOT certify the down and locked position of the landing gear - the visual inspection during low pass should be done by qualified personnel. If not possible, the tower controller should provide information about landing gear not extended or only partly extended to the aircraft concerned;

· have direct contact with aircraft operator’s technical representative (if possible) - any result of a visual inspection should be passed to the crew without delay;

· clear RWY when ACFT 50 track kilometres from touchdown;

· keep safety strip clear and towing equipment on stand-by as appropriate;

· maintain close coordination with ground emergency units - an early call could facilitate the effective deployment of manpower; 

 

If a crew has declared gear problems, the controller may anticipate:

· Holding pattern request for preparation and execution of manual extension;

· The necessity of time and place to perform specific maneuvers with the purpose of full extension;

· One or multiple low passes for visual inspection;

· Low speed approach;

· Runway blockage after landing.

 

IX. Complete the sentences.

1. Landing gear system is essential because……………………………………..

2. Landing gear problems can be caused by technical reasons…………………..

3. Landing gear problems can be caused by outside factor………………………

4. Landing gear problems can be caused by human factor………………………

5. There are various gear problems………………………………………………

6. If gear is not extended…………………………………………………………

7. If gear is not retracted…………………………………………………………

8. Belly landing is………………………………………………………………..

9. If landing gear is not locked…………………………………………………..

10. Low pass is……………………………………………………………………

11. If tire burst…………………………………………………………………….

12. ATCs have to………………………………………………………………….