84 UNITED TECHNOLOGIES CORPORATION NOTES TO CONSOLIDATED FINANCIAL STATEMENTS We provide service and warranty policies on our products and extend performance and operating cost guarantees beyond our normal service and warranty policies on some of our products  particularly commercial aircraft engines. In addition  we incur discretionary costs to service our products in connection with specific product performance issues. Liabilities for performance and operating cost guarantees are based upon future product performance and durability  and are largely estimated based upon historical experience. Adjustments are made to accruals as claim data and historical experience warrant. The changes in the carrying amount of service and product warranties and product performance guarantees for the years ended December 31  2011 and 2010 are as follows: The following table summarizes the credit risk profile by creditworthiness category for aerospace long-term receivable balances at December 31  2011 and 2010: For 2011  the increase reflected within “Other” in the above table primarily related to the finalization of purchase accounting associated with the December 2010 acquisition of Clipper. In view of the risks and costs associated with developing new engines  Pratt & Whitney has entered into certain collaboration arrangements in which sales  costs and risks are shared. Sales generated from engine programs  spare parts  and aftermarket business under collaboration arrangements are recorded as earned in our financial statements. Amounts attributable to our collaborative partners for their share of sales are recorded as an expense in our financial statements based upon the terms and nature of the arrangement. Costs associated with engine programs under collaborative arrangements are expensed as incurred. Under these arrangements  collaborators contribute their program share of engine parts  incur their own production costs and make certain payments to Pratt & Whitney for shared or joint program costs. The reimbursement of the collaborators’ share of program costs is recorded as a reduction of the related expense item at that time. As of December 31  2011  the collaborators’ interests in all commercial engine programs ranged from 12% to 48%  inclusive of a portion of Pratt & Whitney’s interests held by other participants. Pratt & Whitney is the principal participant in all existing collaborative arrangements. There are no individually significant collaborative arrangements and none of the partners exceed a 31% share in an individual program. In September 2011  Pratt & Whitney announced a new collaboration with JAEC and MTU to provide the PurePower PW1100G-JM engine for the Airbus A320neo program. Under the collaboration agreement  MTU will hold an 18% share and be responsible for the engine’s low pressure turbine and We accrue for costs associated with guarantees when it is probable that a liability has been incurred and the amount can be reasonably estimated. The most likely cost to be incurred is accrued based on an evaluation of currently available facts  and where no amount within a range of estimates is more likely  the minimum is accrued. In accordance with the Guarantees Topic of FASB ASC  we record a liability for the fair value of such guarantees in the balance sheet. We also have obligations arising from sales of certain businesses and assets  including from representations and warranties and related indemnities for environmental  health and safety  tax and employment matters. The maximum potential payment related to these obligations is not a specified amount as a number of the obligations do not contain financial caps. The carrying amount of liabilities related to these obligations was $138 million and $139 million at December 31  2011 and 2010  respectively. For additional information regarding the environmental indemnifications  see Note 17 to the Consolidated Financial Statements. * Represents IAE’s gross obligation; at December 31  2011 and 2010 our proportionate share of IAE’s obligations was 33%. NOTE 16: COLLABORATIVE ARRANGEMENTS (Dollars in millions) 2011 2010 Balance as of January 1 $ 1 136 $1 072 Warranties and performance guarantees issued 475 440 Settlements made (440) (379) Other 297 3 Balance as of December 31 $1 468 $ 1 136 NOTE 15: GUARANTEES We extend a variety of financial guarantees to third parties. As of December 31  2011 and 2010 the following financial guarantees were outstanding: 2011 2010 (Dollars in millions) Maximum Potential Payment Carrying Amount of Liability Maximum Potential Payment Carrying Amount of Liability IAE’s financing arrangements* (See Note 4) $989 $20 $992 $12 Commercial aerospace financing arrangements (See Note 4) 323 30 336 12 Credit facilities and debt obligations— unconsolidated subsidiaries (expire 2012 to 2034) 239 3 225 3 Performance guarantees 33 — 40 — Commercial customer financing arrangements — — 191 1 December 31  2011 December 31  2010 (Dollars in millions) Long-term trade accounts receivable Notes and leases receivable Long-term trade accounts receivable Notes and leases receivable A—(low risk  collateralized / uncollateralized) $201 $ — $193 $ — B—(moderate risk  collateralized / uncollateralized) 3 295 5 336 C—(high risk  collateralized / uncollateralized) — 70 — 80 D—(in default  uncollateralized) — — — — Total $204 $365 $198 $ 416