• Aviocentro

    Aeronautical Integral service. From Córdoba Argentina towards nationwide.


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CORROSION PROCESS IN AGRICULTURAL AEROPLANES
 
 
Aims:
1.        To achieve a SECURE operation
2.        Rational administration of the plane affecting the amortization of the aeroplane deadline.
3.        To guarantee the flight performances specified by the manufacturer.
 
The main steps to sort out a problem are:
 
1. Identification        2. Understand it         3. Mark it out
 
To understand what corrosion process means we must talk briefly of metallic alloys, that
are some of the materials which take part on our aeroplane structures.
 
 
Most of these alloys are not found in natural state. To get them, a group of minerals must be subjected to a process whose tendency is to separate some elements and combine them, on certain proportions, to others.
The purpose of this process is to give particular characteristics / specific properties which will be required when they are working as part of the structure.
Example: High resistance to the traction, under weight etc.
If the alloy obtained is not preserved, tends - by natural process - to separate itself and
goes back and combines with other elements with a better affinity.  This return of the elements to its combination in natural state is the properly corrosion process.
This process provokes an alteration in the properties of the materials.
 
So, the join wing-fuselage is designed to support determined capacity of efforts - what, for you pilots, means certain radium of rotation on a certain velocity and with certain configuration.
If the same join wing-fuselage had suffered a corrosive process, it would be seen altered and lowered its capacities to support certain efforts.
WARNING: The join wing-fuselage will not support the efforts for which it was designed because of the corrosion effects; therefore, the manoeuvring which was taken on account in the manual of flight of the aircraft would not be permitted today. If the pilot ignores that his tool -the aircraft- is not the same, we are next to suffer the consequences of an accident.
 
We, who design / interpret plans of maintenance, design solutions to avoid the separation of the elements which constitute the alloys, and avoid, in this way, the loss of the properties which identified them.
 
The most common reasons of corrosion are:
- Not well painted aeroplanes (bad maintenance)
- Insect impacts (dirty aircrafts)
- Pressure values of the bolts different from the ones specified by the manufacturer.
- Battery gasses on the cables of command.
- Spilling of mixtures for aero applications on clinched unions.
- Different alloys in direct contact.
- Relative displacements on the clinched unions.
 
So, being identified and understood the problem: what can I do as a pilot / owner to minimise these undesirable effects that threaten the security and profitability of my business?
 
 
 
FUNDAMENTAL AND ELEMENTARY:
 
Maintain the plane clean, painted and lubricated. Control these three aspects every day.
 
Everybody knows that not every day and not every time are propitious for air applications.
Therefore, when the conditions are propitious and the engineer agronomist demands, IT IS NECESSARY TO GO OUT AND APPLY IT, and so we have working days that start at 5:30 in the morning and finish at 9:30 pm, so we get around 16 working hours without stopping. Of course, the pilot will only look forward to having a shower and going to bed.
If we do not have a minimum support team on land, will exist the possibility for the plane to spend all the night filthily, with insect impacts and spilled with that mixture which is ideal to carry the product that will control the disease of the crops, but has an undesirable effect on the plane structure:  to promote the corrosion process with the undesirable effects above described.
 
 
The mentioned effects are not shown in the short term. Maybe we could collect the realized applications and apparently the operation would be rapid and profitable.
The problem becomes evident when the plane is checked and above all to those people who think maintenance as a cost and not as an investment in the business.
 
Understood it, identified and marked the problem out.
 
My positive or negative attitude in front of the process of corrosion effects will affect the security and profitability of the operation.
 
Situations:
 
1.        Experienced pilot + Experienced, responsible person of the maintenance = IDEAL / PROFITABLE
 
2.        Inexpert pilot + Inexpert person of the maintenance = INSECURE / UNPROFITABLE
 
A concise and complete corrosion treatment can be found in the Advisory Circular AC 43/4 of the FAA / Aircraft Corrosion Controls. You can also consult the person in charge of maintenance of your trustfulness.
 
 
Author: Eng. Santiago Centeno

Tel: 0351 156 549 122
E-mail: This e-mail address is being protected from spambots. You need JavaScript enabled to view it.
 
Aeronautical Mechanic Engineer
Mat. Prof. 0812 / Reg. D.N.A. 5247
Professor in the Chair of Maintenance of Aircraft, Faculty of Engineering, National University of Córdoba
Person in charge of the task of maintenance performed in the Aerotaller Aviocentro, qualification D.N.A. 1B-440.