About 90% of our net 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.
In our business, we saw another quarter of sequential improvement in commercial aftermarket revenues with total commercial aftermarket revenues up 14% over Q3.
We had strong operating cash flow generation of almost 300 million and closed the quarter with approximately 4.8 billion of cash.
However, based on the quite limited due diligence information that was made available and the resulting uncertainties, we could not conclude that moving forward with an offer of 900 pence per Meggitt share would meet our long-standing goals for value creation and investor returns.
These additional diligence requests were very similar to what was typically received in the almost 90 acquisitions we have done over the life of the company.
Given what we know today, our teams are planning for our commercial aftermarket revenue to grow in the 20 to 30% range, planning for our commercial aftermarket revenue to grow in the 20 to 30% range.
We expect full year fiscal 2022 EBITDA margins to be roughly in the area of 47%, which could be higher or lower based on the rate of commercial aftermarket recovery.
As a final note, this margin guidance includes the unfavorable headwind of our recent Cobham acquisition of about 0.5%.
As a reminder, and consistent with past years, with roughly 10% less working days than the subsequent quarters, fiscal year 2022 Q1 revenues, EBITDA, EBITDA margins are anticipated to be lower than the other three quarters of fiscal year 2022.
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 revenue increased approximately 1% in Q4 and declined approximately 25% for full year fiscal 2021 compared with prior year periods.
Sequentially, both Q4 revenue and bookings improved approximately 5% compared to Q3.
Total commercial aftermarket revenue increased by approximately 41% in Q4 and declined approximately 18% for full year fiscal 2021 when compared with prior year periods.
Sequentially, total commercial aftermarket revenues grew approximately 14%, and bookings grew more than 25%.
IATA recently forecast a 39% decrease in revenue passenger miles in calendar year 2022 compared to pre-pandemic levels.
Within IATA's estimate is the expectation that domestic travel will be back to 93% of pre-pandemic levels in calendar year 2022.
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 2% in Q4 and approximately 5% from full year fiscal 2020 when compared with prior year periods.
First, in regard to profitability for fiscal '21, EBITDA as defined of about 636 million for Q4 was up 28% versus prior year Q4.
On a full year basis, EBITDA as defined was about 2.19 billion, down 4% from the prior year.
EBITDA as defined margin in the quarter was approximately 49.7%.
This represents sequential improvement in our EBITDA as defined margin of almost 400 basis points versus Q3 of '21.
As a result of the accounting treatment applied, roughly 130 million of revenue and 25 to 30 million of EBITDA as defined from these divested operating units remains in our FY '21 results.
This revenue and EBITDA will obviously not carry over into FY '22.
On cash and liquidity, we ended the year with approximately 4.8 billion of cash on the balance sheet, and our net debt-to-EBITDA ratio was seven times.
In the early days of October, we repaid the 200 million revolver drawdown that we made at the onset of COVID back in April of 2020.
Pro forma for the revolver paydown, our cash balance is 4.6 billion.
Interest expense is expected to be about 1.08 billion in FY '22.
On taxes, our fiscal '22 GAAP and cash rates are anticipated to be in the range of 21 to 24%, and the adjusted tax rate will be a few points higher and in the range of 26 to 28%.
On the share count, we expect our weighted average shares outstanding will increase by about 800,000 shares to 59.2 million in FY '22, and that assumes no buybacks occur during the fiscal year.
As we traditionally define our free cash flow from operations at TransDigm, which as a reminder is our EBITDA as defined less debt interest payments, less capex, less cash taxes, we expect this metric to be in the 1 billion area, maybe a little better, in fiscal '22.

Summary:
This revenue and EBITDA will obviously not carry over into FY '22.