Deployment of our lean portfolio management toolset, which significantly accelerates the efficiency and impact of R&D investments, achieved a greater than 40% increase in our on-time program delivery.
The application of FBS and digital analytics and search optimization generated 25% growth in digital traffic, from pre-pandemic levels across the portfolio.
Meanwhile, the use of FBS growth tools has accelerated innovation at Fluke Health Solutions over the past 18 months and continues to drive excellent top line performance.
As we highlighted at our Investor Day, we see substantial runway across our $40 billion served market for disciplined capital allocation to accelerate our strategy.
Turning to a quick summary of the results in the quarter on slide four, we generated year-over-year total revenue growth of 26.7% as revenue strength exceeded the high end of our guidance.
Adjusted operating margin was 22.2% while adjusted earnings per share was $0.66, representing a year-over-year increase of 53.5%.
Given the outperformance for both top line and our adjusted operating margin we delivered $282 million of free cash flow, which represented 118% conversion of adjusted net income.
iOS posted total revenue growth of 31.2% in the second quarter.
This included mid-20% core growth in North America, low 30% core growth in Western Europe and low 20% core growth in China.
Fluke's core revenue increased in the mid-30% range.
The company's iNet offering remained resilient, increasing by mid single-digits with net retention solidly above 100%.
Gordian increased by mid-teens, driven by low 20% growth in the procurement business and high teens growth in estimating.
Precision Technologies segment posted a total revenue increase of 25.1% in the second quarter.
This included low 20% growth in North America, mid-20% growth in Western Europe and mid-teens growth in China.
Tektronix increased by approximately 30%, with another quarter of strong demand across its product businesses, including accelerating point-of-sale trends in each of its major regions.
PacSci EMC grew in the low 20% range, with the business seeing some alleviation of the COVID-related shutdowns and approval delays that impacted shipments in previous quarters.
Total revenue increased 21.8%, including 11% core growth.
While elective procedure volumes increased on a year-over-year basis, Q2 volumes came in a bit lower than expected at approximately 93% of pre-COVID levels, which was consistent with the Q1 exit rate.
ASP also continued to expand its global installed base of terminal sterilization capital equipment, which grew at a 3.5% annualized rate in Q2.
Censis increased in the mid-20% range with mid-teens growth in its CensiTrac SaaS offering as well as strong growth in its professional services business.
FHS saw high-teens growth from its Optimize and OneQA software solutions, which benefited from accelerated growth investments over the last 18 months.
Adjusted gross margins were 57.3%, up 100 basis points on a year-over-year basis.
This increase reflected 130 basis points of price realization as we delivered another quarter of solid performance managing price cost across the portfolio.
Q2 adjusted operating profit margin was 22.2%, 170 basis points above the high end of our guidance, also driven by stronger volume and high associated fall-through.
We reported 240 basis points of core operating margin expansion, including 570 basis points of core OMX at the iOS segment.
On Slide eight, you can see that in the second quarter, we generated $282 million of free cash flow, representing a 118% conversion of adjusted net income.
Free cash flow over the trailing 12 months increased 15% to $943 million.
Today, our net leverage is approximately 1 time and we expect net leverage to be around 1.2 times at year end, including the funding of the acquisition of the service channel, but excluding any additional M&A.
For the full year, we now expect adjusted diluted net earnings per share to be $2.65 to $2.75, representing a year-over-year growth of 27% to 32% on a continuing operations basis.
This assumes total revenue growth of 13.5% to 15%, adjusted operating profit margins of 22.5% to 23.5%, and an effective tax rate of 14% to 14.5%.
It also assumes total revenue growth of 8.5% to 11% in the second half of 2021.
We continue to expect free cash flow conversion to be approximately 105% of adjusted net income for the full year.
We are initiating third quarter adjusted diluted net earnings per share guidance of $0.62 to $0.66, representing year-over-year growth of 24% to 32%.
This assumes total revenue growth of 11.5% to 14.5%, adjusted operating profit margin of 21.5% to 22.5% and an effective tax rate of 14% to 14.5%.
For the third quarter, we expect free cash flow conversion to be approximately 105% of adjusted net income.
During our Investor Day program on May 19, we introduced an accelerated greenhouse gas reduction goal, which now targets a reduction of 50% in greenhouse gas intensity for Scope 1 and Scope 2 emissions by 2025 relative to our 2017 base year.

Summary:
For the full year, we now expect adjusted diluted net earnings per share to be $2.65 to $2.75, representing a year-over-year growth of 27% to 32% on a continuing operations basis.
We are initiating third quarter adjusted diluted net earnings per share guidance of $0.62 to $0.66, representing year-over-year growth of 24% to 32%.