About 90% of our sales are generated by proprietary products, and over [ three-quarters ] of our net sales come from products for which we believe we are the sole source provider.
But in Q2, we acquired the Cobham Aero Connectivity business for an enterprise value of $965 million.
On the divestiture front, in the last 60 days, we signed agreements to sell three additional, less proprietary and mostly defense businesses for about $240 million.
Collectively, these businesses have revenues of roughly $180 million and EBITDA margins in the low 20%.
In our business, we saw another quarter of sequential improvement in commercial aftermarket revenues with total commercial aftermarket revenues up 12% over Q1.
In the commercial market, which typically makes up close to 65% of our revenue, we will split our discussion into OEM and aftermarket.
Our total commercial OEM market revenue declined approximately 43% in Q2 when compared with Q2 of the prior-year period.
On a positive note, Q2 bookings demonstrated strong sequential improvement of over 20% compared to Q1 bookings and solidly outpaced sales.
Total commercial aftermarket revenues declined by approximately 39% in Q2 when compared to prior-year Q2.
To repeat, sequentially, total commercial aftermarket revenues grew approximately 12% in Q2, another encouraging data point.
Q2 bookings sequentially improved almost 30% and solidly outpaced sales.
IATA's most recent forecast expects that calendar-year 2021 revenue passenger miles will be 57% below 2019, but we are cautiously optimistic.
Now let me speak about our defense market, which, traditionally, is at or below 35% of our total revenue.
The defense market revenue, which includes both OEM and aftermarket revenues, grew by approximately 8% in Q2 when compared with the prior-year period.
EBITDA as defined of about $519 million for Q2 was down 23% versus prior Q2.
EBITDA as defined margin in the quarter was approximately 43.5%.
We were able to improve our EBITDA as defined margin approaching 100 basis points sequentially despite the acquisition dilution from the recent Cobham acquisition of about 100 basis points as well.
We are still not in a position to issue formal fiscal 2021 sales EBITDA as defined in net income guidance at this time.
We assume a steady increase in commercial aftermarket revenue going forward and expect full-year fiscal 2021 EBITDA margin roughly in the area of 44%, which could be higher or lower based on the rate of commercial aftermarket recovery.
For the quarter, organic growth was negative 20%, driven by the declines in our commercial end markets and despite some healthy defense growth in the quarter.
That is, we still anticipate our GAAP cash and adjusted rates to be in the 18% to 22% range.
On interest expense, we now expect the full-year charge to be $1.06 billion, reduced from prior guidance, primarily for the refinancing activity completed this year.
Free cash flow, which we traditionally define at TransDigm as our EBITDA as defined less cash interest payments, cash capex and cash taxes, was roughly $146 million.
In line with our prior November guidance, we still expect this amount to be in the $800 million area, maybe a little better for our fiscal '21.
We ended the second quarter with $4.1 billion of cash, down from $4.9 billion at last quarter's end.
Note that last quarter's $4.9 billion balance was prior to the Cobham acquisition for an enterprise value of $965 million that closed on January 5.
Pro forma for the closing of this acquisition, our Q2 net debt-to-LTM-EBITDA ratio was 8.2 times.

Summary:
We are still not in a position to issue formal fiscal 2021 sales EBITDA as defined in net income guidance at this time.