Integral mechanical unit classification of drilling rigs on chassis confirmed under heading 8430, while extended limitation was rejected.

A drilling rig mounted on a modified motor vehicle chassis was treated as an integral mechanical unit, because the chassis had been cut, strengthened and adapted for hydraulic jacks and power transmission; it was therefore classifiable under sub-heading 8430.00 and not under 8705.00. The extended limitation period under section 11A could not be invoked without proof of suppression or wilful misstatement with intent to evade duty, so the duty demand failed, and the associated penalty under section 11AC and interest under section 11AB also could not stand. The section 11D demand was upheld because it was not contested.

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Issues: (i) Whether drilling rigs mounted on motor vehicle chassis were classifiable under sub-heading 8430.00 or sub-heading 8705.00 of the Central Excise Tariff Act, 1985. (ii) Whether the duty demand under section 11A, the penalty under section 11AC, and the interest demand under section 11AB were sustainable. (iii) Whether the demand under section 11D was liable to be confirmed.

Issue (i): Whether drilling rigs mounted on motor vehicle chassis were classifiable under sub-heading 8430.00 or sub-heading 8705.00 of the Central Excise Tariff Act, 1985.

Analysis: The classification turned on the extent of integration between the drilling rig and the chassis. The chassis was modified by cutting and altering the propeller shaft, adjusting the length, strengthening the structure, and adapting it for hydraulic jacks and power transmission to the drilling system. On these facts, the chassis was not merely a vehicle carrying a mounted machine, but part of an integral mechanical unit specially designed for the drilling function. The exclusion in Chapter 87 for self-propelled wheeled machines forming an integral unit supported exclusion from heading 87.05.

Conclusion: The goods were rightly classifiable under sub-heading 8430.00, and not under sub-heading 8705.00.

Issue (ii): Whether the duty demand under section 11A, the penalty under section 11AC, and the interest demand under section 11AB were sustainable.

Analysis: The extended period could be invoked only on proof of suppression of facts or wilful misstatement with intent to evade duty. The record showed that, during the relevant period, the classification issue had been decided in the assessee's favour in earlier Tribunal decisions, and the departmental case rested on a later change in legal position. In the absence of suppression or misdeclaration, the larger period could not be sustained. Once the duty demand failed, the penalty and consequential interest could not survive.

Conclusion: The duty demand under section 11A, the penalty under section 11AC, and the interest demand under section 11AB were not sustainable.

Issue (iii): Whether the demand under section 11D was liable to be confirmed.

Analysis: The demand under section 11D was not contested in the hearing and was therefore upheld without further examination.

Conclusion: The demand under section 11D was confirmed.

Final Conclusion: The appeal succeeded on classification, limitation, penalty, and interest, but failed in respect of the section 11D demand, resulting in partial relief to the assessee.

Ratio Decidendi: A drilling rig mounted on a chassis is classifiable under heading 84.30 when the chassis and drilling mechanism are so integrated that they form an integral mechanical unit, and the extended limitation period under section 11A requires affirmative proof of suppression or wilful misstatement with intent to evade duty.

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