India's manufacturing sector expanded sharply in September, ending a three-month slowdown as robust demand drove the fastest growth in factory activity in seven months, revived hiring and lifted business confidence, a private survey showed on Thursday. * The HSBC India Manufacturing Purchasing Managers' Index (PMI), compiled by S&P Global, jumped to 55.1 in September from a five-year low of 52.8 in August but was lower than a preliminary estimate of 55.7. The reading was the highest since February.