Changes in Estimates

The Company has a Company-wide quarterly Estimate at Completion (EAC) process in which management assesses the progress and performance of the Company's contracts. This process requires management to review each program’s progress towards completion by evaluating the program schedule, changes to identified risks and opportunities, changes to estimated contract revenues and estimated contract costs over the current contract block and any outstanding contract matters. Risks and opportunities include management's judgment about the cost associated with a program’s ability to achieve the schedule, technical requirements (e.g., a newly-developed product versus a mature product) and any other contract requirements. The majority of the Company's fixed priced contracts are life of aircraft program contracts. Due to the span of years it may take to complete a contract block and the scope and nature of the work required to be performed on those contracts, the estimation of total revenue and costs at completion is complicated and subject to many variables and, accordingly, is subject to change. When adjustments in estimated total contract block revenue or estimated total cost are required, any changes from prior estimates for delivered units are recognized in the current period as a cumulative catch-up adjustment for the inception-to-date effect of such changes. Cumulative catch-up adjustments are driven by several factors including improved production efficiencies, assumed rate of production, the rate of overhead absorption, changes to scope of work and contract modifications. When estimates of total costs to be incurred on a contract block exceed estimates of total revenue to be earned, a provision for the entire loss on the contract block is recorded in the period in which the loss is determined. Changes in estimates are summarized below:



Changes in Estimates	December 31, 2016		December 31, 2015		December 31, 2014
Favorable (Unfavorable) Cumulative Catch-up Adjustments by Segment
Fuselage	13.6		16.1		14.8
Propulsion	(0.4	)	22.8		18.8
Wing	23.4		2.7		26.8
Total Favorable Cumulative Catch-up Adjustment	36.6		41.6		60.4

(Forward Loss) and Changes in Estimates on Loss Programs by Segment
Fuselage	(133.4	)	8.7		9.9
Propulsion	10.1		2.4		16.5
Wing	5.1		(0.3	)	(0.3	)
Total (Forward Loss) and Change in Estimate on Loss Program	(118.2	)	10.8		26.1

Total Change in Estimate	(81.6	)	52.4		86.5
EPS Impact (diluted per share based on statutory rates)	(0.40	)	0.24		0.38

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(1) Includes ($141.8) forward loss charge on the A350 XWB program for the twelve months ended December 31, 2016.

2016 Changes in Estimates

Favorable cumulative catch-up adjustments for the periods prior to 2016 were primarily driven by productivity and efficiency improvements, favorable cost performance, mitigation of risk on maturing programs and favorable pricing negotiations on a maturing program.

During the second quarter of 2016, Spirit signed a memorandum of agreement with Airbus (the "Airbus 2016 MOA") which, in part, materially reset the pricing for 800 units on the A350 XWB Fuselage and Wing requirements contracts. The Airbus 2016 MOA was negotiated to economically compensate Spirit for significant engineering changes to aircraft design. The new pricing provided the Company with a higher degree of certainty of revenue that will be realized over the 800 unit contracts. Further, the Company analyzed A350 XWB market demand using third party publications as well as Airbus firm orders which indicated that the sustained demand for the A350 XWB program was in excess of 800 units. The Company determined that due to the higher degree of precision of the A350 XWB revenue along with the strong, sustained market demand, it was appropriate to extend the accounting block quantity to 800 units in the second quarter of 2016. The contract block quantity change was made in accordance with applicable accounting guidance as well as the Company’s accounting policies and past practices. As a result of the Airbus 2016 MOA, the Company updated its estimated revenues that will be realized over the 800 unit A350 XWB Fuselage and Wing contract accounting blocks.

While the Company continued to make progress on the A350 XWB Fuselage program, the Company experienced various disruption and production inefficiencies that exceeded estimates made in previous quarters primarily related to achieving production rate increases. As a result of these disruptions and inefficiencies, cost estimates were updated in the second quarter of 2016 to account for increased labor costs in fabrication and assembly and expedited shipping costs to meet current and future customer production rate increases. The Company also updated its estimates in the second quarter of 2016 due to uncertainty of supply chain cost reductions and achievement of cost affordability projects. The changes in revenue and cost estimates during the second quarter of 2016 resulted in a net forward loss charge of ($135.7) on the A350 XWB program. Increased scrap and rework as well as increased production labor costs resulted in an additional net forward loss charge of ($6.1) recorded on the A350 XWB program during the fourth quarter of 2016.

For the twelve months ended December 31, 2016, the changes in revenue and cost estimates during the second and fourth quarters of 2016 (as described above) resulted in a net forward loss charge of ($141.8) on the A350 XWB program. The Company could record additional forward loss charges if there are further changes to revenue and cost estimates and/or if risks are not mitigated.

2015 Changes in Estimates

Favorable cumulative catch-up adjustments for the periods prior to 2015 and changes in estimates on loss programs were primarily driven by productivity and efficiency improvements, favorable cost performance, mitigation of risk, benefits from increased production rates related to the absorption of fixed costs and favorable pricing negotiations on a maturing program. Forward loss charges were due to a production rate decrease on a mature program.

2014 Changes in Estimates

Favorable cumulative catch-up adjustments for the periods prior to 2014 and changes in estimates on loss programs were primarily driven by productivity and efficiency improvements, favorable cost performance, mitigation of risk, benefits from increased production rates related to the absorption of fixed costs, increased statement of work on mature programs and favorable pricing negotiations on a maturing program.