Rubber Journal Asia Tyre Sector
Tyres in the sky The “disappearance” of the Malaysian
Ty r e m aintenance hile experts debate on what ex a c t l y c a u s e d the mishap on Malaysia’s flags h i p c a r r i e r , t he incident has spark ed a wak e-up c a l l f o r t h e aviat ion indust ry . Not only are t he av a i l a bl e t echnolog ies for t he sect or b eing pu t un d er scrut iny , b ut lik ewise t he qualit y of a i rc ra f t maint enance is also b eing hig hlig ht e d . Ty res, which b ear t he full load of t h e aircraft especially during landing , seem t o be a fact or in t he list of common causes o f a v i a t i o n disast ers. There have b een incidence s o f bl ow outs or burning tyres in airplanes, c a u s i n g loss of pressure, hydraulic failure, s t r u c t u r a l damage and loss of aircraft control. D u r i n g taxiing, tyres must provide a stable, c u s h i o n e d ride while resist ing heat g enerat ion, a bra si o n and wear. At take-off, the tyre struc t u r e m u s t be able to endure not only the aircra f t l o a d but also the forces generated at high a n g u l a r velocit ies. Landing requires t he t y re t o a bsorb impact shock s while also t ransmit t in g h i gh dy namic b rak ing loads t o t he g round . A l l of t h i s must b e accomplished while providi n g a l o n g, dependable, reliable, service life. Thus, an important part of aircraf t maintenance is that tyres should be c h e c k e d f o r cy cles, pressure check s and underg o regul a r maint enance inspect ions. Just lik e t h e a ut omo t i v e sect or where proper air pressure ma i n t en a n c e is a must for t y res, even for an airline i t i s required t o achieve opt imum perform a n c e o f i t s tyres. It not only enhances the tyre l i f e , l a n d i n g performance b ut also schedule reliabi l i t y. Not only airplane tyres are vulner a b l e t o cruising risk s. According t o t he 2012 repo rt undert ak en b y t he US Natio nal Hig h w a y T ra ffi c Saf ety Adm inistr atio n (NHTSA) on t y r e - r e l a t e d pre-crash fact ors, “t y res should b e in go od condition, in order for a vehicle to h a n d l e s a f e l y and t o use fuel economically .” It stresses that regular monitoring a s w e l l as maint enance of vehicle t y res can prev en t road disasters such as what tyre blo w o u t s o r failure (due t o under or over inflat io n , bel ow recommended pressure or inadequat e t r e a d dept h). What t hese challeng es conclud e i s t h a t tyres must be maintained.
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Airlines Boeing 777 on 8 March 2014 has provoked several possibilities. While not connected, this incident highlights that maintenance of aircraft tyres is important. Aviation tyres represent another small but high margin niche market, since it is also the most technically demanding, with the tyres on commercial jets having to sustain loads similar to large earthmovers, but at speeds more common to Formula 1 racing cars. Even so, there are three separate markets, each with specific and different requirements: commercial, military and general aviation, says Angelica Buan in this article.
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i r t r a n spo r t has s hown c ons is ten t growt h f o r mo r e t h an 50 years . H owever, there a r e i n c r e a si n g p res s u res on th e ind us try, wit h c h a n g e s i n i t s s truc tu re and th e c om p os it ion o f it s f l e e t s. T h is will in evitably affec t the d e m a n d f o r t y r es in terms of quantity and, m o r e i m po r t a n t ly, d es ign q u ality. N e v e r t h e l e s s, headed for a brighter horizon, m a r k e t a n a l y st s s u gges t that the global aircraft t y r e m a r k e t i s p ois ed for growth. Ma r k e t r e se arc h firm L u c in tel’s forecast for t h e i n du st r y t h rou gh 2020 s ugges ts m oderat e gr o w t h o f 3 . 2 % th at is ex p ec ted to reac h an e s ti m a t e d US $ 1.1 billion d uring the p eri od. It s a y s t h a t a n i n c reas ed d elivery of c om mercial, m i l i t a r y a n d g eneral airc raft will s p ur the d e ma n d, l e d a l so by th e rep lac em en t in dust ry . T h e r e po r t e x p lain s th at c om m erc ial airline p a sse n g e r t r a f f ic is ex p ec ted to grow over t he n e x t 2 0 y e a r s t o 1.3 billion by 2030, yielding gr o w t h o f l a n ding an d take-off p lan es , which c o n s e q u e n t l y will increase demand for aircraft t y r e s du e t o w ear an d tear.
Taking a lo o k inside an air cr af t ty r e ircraft tyres fall into two distinc t t echnolog ies: b ias (also k nown a s c ross pl y) and radial. Bias and radial tyres are s i g n i f i c a n t l y
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Rubber Journal Asia Tyre Sector
d i f f e r e n t t o e a c h other and both tec h nolog ies o f f e r o p e r a t o r s features and benefits that m i g h t b e c o n s i dered agreeable for particular a p pl i c a t i o n s. T h e airc raft tyre is a c om p osit e s tr u c t u r e o f t h r ee bas ic m aterials : ru bber, n ylo n c o r d a n d s teel. W h i l e ma n y of the c om p on ents of bias a n d r a di a l t y r e s have th e s am e term in olog y , e a c h t y p e h a s unique components reflecting t h e d i f f e r e n t t e chnologies applied to design, c o m po u n ds a n d m aterials .
Radial aircraft tyre
The bias ply tyre
The b ias ply t y re consist s of casing pl i es running diag onally at approximat e ri gh t a n gl es t o one anot her. The numb er of plies a n d t h e angles at which they are laid dictate s t r e n g t h a n d load capacit y . The lat est hig h-perfor ma n c e bi a s ply aircraft tyres feature inter-tread r e i n f o r c i n g fab ric (ITF ). This provides addit iona l h i gh speed stability, reduces tread distort i o n u n d e r load, protects the casing plies from d a m a g e a n d can act as wear indicat ors on ret read a bl e t yres. According to Dunlop Aircraft Tyres (DAT), bias
Rubber Journal Asia Tyre Sector tyres are currently the most popular tyres fitted by the world’s fleet. Radial aircraft tyres differ to bias aircraft tyres in that the plies all run radially from bead to bead at approximately 90 degrees to the centre-line of the tyre. Angled belt plies are laid between the tread and the top casing ply, resulting in a flatter tread and adding strength to the tyre. Radial tyres can offer low weight but tend to be less retreadable than a bias ply tyre and can exhibit weaker sidewalls. What makes aircraft tyres unique is that they are made under stringent conditions, according to the Aircraft Owners and Pilot Association (AOPA). The Maryland-based organisation shares that every tyre is thoroughly constructed and inspected to ensure it complies with the US Department of Transportation’s Federal Aviation Administration (FAA)’s Technical Standard Order (TSO)C62. In this effect, there is no such thing as a “bad tyre”, AOPA says. For these tyres to meet heat tolerance and required adhesion specifications, close to 100% natural rubber (NR) is required to produce the tyres, according to the Ohio-based Programme for Excellence in Natural Rubber Alternatives (PENRA), which is also undertaking R&D of alternative NR sources, such as the Russian dandelion and guayule, for aviation tyres. Meanwhile, retreading plays a particularly important role in aircraft tyres, since they are subjected to extreme stresses. Aircraft tyres have to withstand a huge strain at speeds of over 250 km/hour and undergo retreading after around 150 take-off and landing manoeuvres. Retreading can take place up to ten times, according to the European Tyre & Rubber Manufacturers Association (ETRMA), which also says that testing procedures are naturally very stringent here, and safety takes top priority. The retreading of aircraft tyres has been the industry standard for commercial airlines for many years and is said to be a standard operating procedure for the military.
Michelin will equip Boeing’s 737 Max 7 and 737 Max 8 with its radial aircraft tyres featuring NZG technology
supplier for Boeing’s 737 Max, the new version of the world’s top selling commercial airplane. Michelin will equip the 737 Max 7 and 737 Max 8 with its radial aircraft tyres with NZG (Near Zero Growth) technology. NZG radial technology promises competitive advantages such as up to 50% more FOD (Foreign Object Damage) resistance; more than 20% reduction in weight compared with a bias crossply tyre, which translates into significant fuel savings for airlines; and up to a 100% increase in the number of landings compared with a bias cross-ply tyre, which means less maintenance downtime for aircraft operators. The 737 Max 8 and 7 aircraft are scheduled to enter the market in 2017 and 2019, respectively. Current combined orders stand at more than 1,300 airplanes. Meanwhile, BF Goodrich was an equally prominent figure in the global tyre sector, but when it divested its tyre business in 1988, Michelin acquired its aircraft tyre division the following year. Inclusive of the deal is the use of the BF Goodrich name. Another major player is Dunlop Aircraft Tyres (DAT), the world’s only dedicated aircraft tyre manufacturer and retreader that exports about 80% of its products, with a large bulk going to the Asian market. Birmingham-based DAT has a tyre distribution and retreading facility in China, Dunlop Taikoo (Jinjiang) Aircraft Tyres. Air carriers from Australia, China, India, Indonesia, Japan, South Korea, Philippines and Taiwan are being served by the Jinjiang facility. Confessing to weaker sales in the UK and Europe, it leverages on the strong sales of military tyres to Asia and the Middle East. At the recent Singapore Airshow, DAT showcased its new radial tyres for regional aircraft, including the Embraer E-Jet and ATR72. The lighter weight of the tyre can offer improved landing life, it said.
Aviation tyre market passes with flying colours he extreme demands put on an aircraft require tyres that are highly engineered and precisely manufactured. As such, there are only a handful of manufacturers in this sector. Among the key players in the industry is French tyre maker Michelin, which supplies bias tyres, radial tyres and tubes for the worldwide aviation community. It has an Asian base in Thailand and says it is a full service tyre supplier for all aviation markets worldwide. Michelin has been selected as an OEM tyre
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