We saw operating income increase by almost 23%, going from roughly $419 million last year to $515 million this year. We saw operating margins expand from 25% last year to 26.2% this year, and we saw EPS increase from $1.97 last year to $2.35 this year.If I look at the key drivers on sales versus last year, certainly, as you'd expect, we had strong aerospace growth of roughly 30%, with 12% coming organically, driven by a 10% increase in OEM and a 25% increase in spares. IGT was also a very strong contributor for us, growing by roughly 15%, but the majority of that coming organically at 13%, and the primary drivers is spares, but we did see growth to a lesser degree on the OEM side. And even though at a smaller base, an area that we want to diversify into, we saw oil and gas sales increase by 35% versus last year, with 15% coming organically. And as we've talked the last couple of quarters, we had lower general industrial sales of 3% versus last year. And again, the significant component in this is coming from the value of the revert nickel that we got last year versus this year. And then you'll see, when we get in the cast, we also had alloy sales going into general industrial, were down versus last year. And all this was partially offset by the acquisitions. Contractual material pass-through was basically flat, and the selling price from our 3 primary mills was down roughly $10 million. And quick update, I'm sure you've seen in the press release that we had a 29,000-ton unplanned outage in Wyman-Gordon. The outage impacted roughly 3 weeks in Q1. You're going to see, it goes into 5 weeks into Q2. We had all the spares needed to complete the repair. And then repairs are going as planned at this point in time, but it was certainly an unplanned outage in the quarter.
If I look sequentially, the 2 significant changes where we did have a slight increase in aerospace, we did have more upside in the aerospace. But certainly, the press outage had an impact on the ability to capture as much of that upside as we wanted to. And we also add in the quarter, sequentially. We got the benefit of RathGibson versus Q4.If I look operationally, we've kind of talked about this, we did have some headwinds. We talked last quarter about the additional pension expense. It's the last time we're going to kind of give a baseline to this, but if I compare it to last year and, again, to Q4, it was roughly an $8-million impact in the quarter. And the current estimate of the cost of the 29K outage in Q1, we estimate to be $4 million to $5 million in the quarter. And this was more from the lost absorption. Certainly, the initial maintenance and certainly some lost sales all played into that number. And even though we did get contribution from both Centra and Rath, up from the margin standpoint, certainly, we're dilutive as most of our acquisitions are on the day we take them over, but certainly, the number of opportunities to move that forward. I think, counting all this, we saw a very solid incremental drop-through in our base businesses, upgraded them 50%. We continued to find numerous opportunities, productivities, scrap and rework, revert utilization, and we're by no means at the end of that. But we did see a strong year-on-year improvement in terms of that performance aspect. And from a dollar standpoint, we obviously did see the additional benefit from the acquisitions. And from a Primus standpoint, we're not only seeing the impact of not being in Q1 last year and in the Q1 this year, but they've also seen strong operational improvements as they've gone through the last 12 months. So from that standpoint, we're kind of getting a double hit, positive hit as we get with Primus.
If I look at sequentially, the same headwinds being the pension -- 2 primary headwinds being the pension and the outage, certainly wanted to put pressure in that. But we did see strong operational improvement from our operations to overcome that headwind, and we were able to drive margins up by 0.7 percentage points.If I look forward, for the company in total, I think we have very solid positions on the base programs. We're on all the key platforms. Certainly, it's something we worked long and hard at for the last 4 or 5 years, to make sure we are properly represented in the right platforms. And with that, we certainly will expect to get a benefit as we move into the next rate increases on the base platforms, and we'd expect to see acceleration from the 787 as it ramps up through next year. We've had good penetration on oil and gas. We started delivering. But having said that, there is a significant amount of product that needs to come through the system in the next 3 to 4 quarters. And we continue to see upside on share opportunities in both aerospace and IGT. And I think if we go back and look at kind of the Wyman-Gordon transaction years ago and the SPS transaction, I think we see the same type of opportunity in terms of getting that aerostructures platforms together, create the business and then certainly go and grow market share in those particular areas. I think even though we did have quite a view -- quite a bit of action on the acquisition front in the course of the last quarter, we are still not an end of opportunities, and I think we'll still expect to see movement on this over the course of the -- again, the next 3 or 4 quarters. Read the rest of this transcript for free on seekingalpha.com