Factors Detrimental to Safety in any Helicopter
Helicopters are inherently dangerous to fly due to the various types of instabilities that are introduced by the main and tail rotors that are rotating at extremely high speeds. Apart from the conventional dangers arising out of an engine failure applicable to all flying machines, the helicopters are additionally prone to catastrophes caused by the failure of the tail rotor. The strength and stability of the tail rotor is the foremost safety factor that needs to be addressed in any helicopter.
A helicopter is in full flying configuration even on ground after the rotors are at their full RPM. There are several ground accidents waiting to happen such as the phenomenon of ground resonance when landing on uneven surfaces and dynamic roll over that is caused by excessive tilting of the rotor disc on ground.
In certain conditions involving the up weight, forward speed and height, the helicopter enters a 'Dead Man's Curve', which is an envelope of flight where it cannot autorotate safely back to earth under any circumstances or skill level of the crew.
Specific Safety Issues in Training Helicopters
The natural instabilities present in a helicopter when coupled with mishandling by trainee pilots drastically shrink the safe flying envelope at a rapid pace. The chances of a novice noticing the development of an emergency situation to initiate corrective actions in time are quite less. This implies that the situations will quickly aggravate in training helicopters as compared to operational machines.
Learning to handle a rotary wing aircraft in the initial stages is one of the most arduous tasks with fairly high chances of mishandling that could lead to the platform hitting obstructions or ground without any forewarning. Such an eventuality has the potential of toppling the machine to complete destruction. Incidents of ground resonance and dynamic rollover are maximum during training sorties.
The trainees are also likely to cause hard and heavy touchdown which may cause the collapse of the undercarriages that are not designed for such shocks. Handling of the machine on ground in gusty wind conditions during training stages is another dangerous situation pertinent to helicopters.
All the above discussed factors must be taken into account while analyzing the safety features in helicopters specifically designed to be employed on training roles.
Some of the Best Contemporary Options Available
Keeping in view the special demands for safety features to be incorporated in order to provide the safest learning helicopter, some of the currently available models can be analysed for their efficacy.
This is one of the most commonly used helicopters in training schools across the world primarily due to the stability of the platform that allows the trainees to have their share of mishandling without actually entering a dangerous situation. However due to shortage of spares and non availability of trained personnel this machine is now being phased out of operations gradually.
Guimbal Cabri G-2
This is a two seated helicopter with a three blade main rotor system and a fenestron tail rotor arrangement for extra safety while being handled by learners. Powered by a Lycoming engine of 180 HP rating this machine is suitable for basic training in the civil as well military helicopter aviation. The easy and forgiving handling characteristics of this helicopter makes it a favorite among the trainee pilots as well as instructors.
The low operating cost coupled with minimal maintenance requirements make the R-44, the world's most favorite training helicopter. This light weight platform runs on a piston engine that provides quick response which is desirable in the learning stages. Its stable qualities in face of gusty winds and immediate response of the flying controls are ideal for trainees who find this platform extremely safe to operate. The autrotative characteristics of the R-44 provide the safest solution against single failures among all the single engine variants of this size.
This model has been specifically designed to be employed as a basic trainer for corporate flying. There are plenty of crashworthy features incorporated into this helicopter including sturdier and safer seating, stronger oleos and self sealing tanks that raise its safety margin tremendously against other options. A huge reserve of power with its 180 HP engine that is always available in this helicopter ensure that it can easily get away from obstructions successfully and additionally the light weight airframe provides it with a superior glide ratio in autorotation after an engine failure in flight.
Selecting the Safest
After having seen the various requirements that must be catered for in order to design the safest learning helicopter and comparing them against the features available in the most commonly used trainers, it can be inferred that not all the requisite qualities will be present in every machine. Thus safety in learning rotary wing aircraft being a combination of several different factors, the two most preferred models that measure up to maximum of these standards are the Robinson R-44 and the Schweizer 300 which are being utilized globally for this specific purpose. Some countries prefer the ageing Alluoette fleet for training new pilots in the military a well as civil spheres, though the relaibilty of these machines has come under severe questioning in the past few years. Since safety in training is a compromise on the performance in operational roles, dedicated models meant exclusively for this purpose need to be developed so as to maintain adequate margin for the errors of the learners.
- Image : Schweizer 300 by Andrew Borrows under public domain
- Image : Robinson R-44 by Arpingstone under public domain
- Image : Guimbal Cabri G-2 by Mumulafrite under public domain
- Federal Aviation Authority (FAA), ” WINGS- Pilot Proficiency Program”, https://www.faasafety.gov/WINGS/pppinfo/
- Flight Training (AOPA), ” Air Safety Institute”, http://www.aopa.org/asf/