Air transport requires special requirements for checking its serviceability and maintenance. This is explain due to the high risk of accidents in the air. This article is based on the recommendations of JSC “ARZ”, the holding company “Russian Helicopters”.
Activities that make up the maintenance of helicopters.
Maintenance of MI-8/17/171 helicopters, as well as their modifications, is not a single operation. This is a set of procedures carried out in different situations that have a specific purpose. Also, maintenance in the Russian Federation is divided into categories depending on the aircraft system:
- to control the condition of the airframe and power plant;
- inspection and maintenance of aviation and radio-electronic devices;
- to control the condition of the chassis;
- to control the condition of the carrier system.
Maintenance of helicopters can be operational or periodic and in the case of its storage: seasonal or special.
Operational maintenance includes the following actions •
- meeting the aircraft ;
- parking arrangement (PA);
- organization of departure the aircraft (OD);
- inspection and maintenance-forms ОВ-1, А-1, А-2,Б.
PA begins if the ship’s crew transfers it for maintenance for more than two hours or when moving it to another location.
OD is performed as a pre-flight preparation of the vessel, without exceptions, without taking into account whether the operational form was carried out.
The ОВ-1 form is carried out in the absence of flights after carrying out the operational form for more than twelve hours, if the helicopter was inspected according to the A-1 form after maintenance.
Maintenance of the A-1 aircraft is carried out:
- when the vehicle is in the air for more than 45 minutes, if there is no need to carry out A-2;
- refueling, with a break between landings of less than 45 minutes;
- termination of flights if the daily flight time is less than 7 hours.
Maintenance of the A-2 aircraft is carried out after:
- the being in the air for more than 7 hours a day, if the deadline for performing periodic maintenance has not come (if the flight is less than 7 hours, the “A-2” form is carried out once every 48 hours when continuing flights);
- carrying out periodic maintenance in any form;
- special maintenance.
Form Б is prescribed after 25 hours spent by the aircraft in the air, with an error of plus or minus 5 hours.
The work performed during maintenance.
All types of actions performed during the maintenance helicopters MI-8/17/171 are performed to ensure the safety of the helicopters , its crew, passengers and cargo. For this reason, for each type of helicopter in the aviation enterprises of the Russian Federation, there are regulations that set the deadlines for carrying out maintenance.
The list of actions performed during periodic maintenance in the Russian Federation includes •
- preliminary preparation;
- diagnostics and repair, if necessary;
- grease works;
- commissioning work.
This type of maintenance of MI helicopters is assigned after a flight of more than 50 hours after the start of flights of the aircraft or repair. It includes the Ф-1 form, in the future, after working out 100, 300, 500 hours of flight, Ф-2, Ф-3 and Ф-4 are performed. The addition of these forms does not depend on the tolerances of the previous forms of the maintenance.
All maintenance operations under consideration have the same tolerance, which is equal to plus or minus 10 flight hours. If the maintenance of MI-series helicopters is carried out by a phased method, the tolerance can be increased to 20 hours for work carried out after 100 hours or more.
The schedule of the inspection of the engines is compiled according to the time of the glider’s flight. If the helicopter needs to replace the engine or other significant parts due to resource depletion, or the aircraft is undergoing maintenance ahead of schedule, repairs and maintenance are carried out, required by the available number of glider hours spent in the air and by the time of:
- the engine;
- airframe elements or wiring that are available only when the engine or component is removed.
In the future, all maintenance of the engine and other helicopter systems is carried out in normal mode, according to a single time schedule. The starting point is the helicopter glider.
Periodic maintenance includes checking the engine, the condition of oils and aggregates that have a limited resource. Elements that have failed are identified and replaced, grease are replaced.
Preparation for storage.
Maintenance of MI-series helicopters during storage is necessary if the helicopter does not rise into the air for some time.
- preparation of aircraft for storage;
- maintenance of 10±2 s•;
- maintenance of 30 ±5 s.;
- 90 days ±10 days;
- 180 days ±30 days;
- preparation of the aircraft for flights after storage.
The tasks of the maintenance include maintaining the working condition of the MI vessel and the ability to quickly prepare it for operation.
This type of maintenance is performed during the preparation of MI-8/17/171 helicopters, in the Russian Federation for the autumn-winter and spring-summer periods. This is due to the difference in the wear of the coating, rubber products and other features of the operation of aircraft at different temperatures.
Such maintenance allows you to reduce the wear of structures and improve flight safety. Provides for the following:
- fault detection;
- restoration of the anticorrosive layer ;
- minor repairs;
- elimination of corrosion;
- adjusting the tension of the rope control;
- checking the sound warning alarm system;
- restoration of covers, plugs, etc.
The main part of helicopter malfunctions at high temperatures occurs in the chassis design. The reason for this in most cases is the excessive pressure in the tires of the aircraft, which leads to jumps and throws of helicopters when moving. This leads to a weakening of the fastener of the chassis structure . Such malfunctions are fraught with the occurrence of emergency situations, therefore they are subject to immediate elimination. These include such easily removable, but very dangerous flaws as:
- increased wear and tear;
- tire aging.
To minimize these manifestations, it is recommended to adjust the tire pressure at the lower limit. This will reduce their wear, reduce their aging, and reduce the loosening of the chassis fasteners.
Special maintenance does not have a time frame and is assigned when special circumstances occur. It is carried out to confirm the safety of further use of MI-8/17/171 Helicopters, or to bring it into proper condition. This type of maintenance is assigned in the event of the following events
- getting into a zone of high turbulence;
- covering the helicopter with ice;
- damage to the aircraft by a lightning strike;
- rough fit;
- capture of an aircraft by a storm wind on the ground;
- carrying out major repairs;
- replacement of the motor, gearboxes, screw bushing.
To carry out these actions, there are technological maps that regulate the composition and procedure for carrying out maintenance. They are included in the ” Manuals for the technical operation of MI-8T helicopters (MTV/AMT, and their modifications)”, and are included in the instructions for maintenance technologies and storage of component parts.
Admission to flights of aircraft subjected to these conditions without passing a special maintenance is prohibited in the Russian Federation.
Special maintenance is assigned by a commission established by the company that operates the aircraft. The Commission analyzes the data on the events that have occurred, examines the aircraft and makes a decision on the composition and nature of maintenance, fixing the detected malfunctions in the defective list. On the basis of this document, maintenance and repair of the helicopter is carried out.