Airworthiness Directive · Amendment 39-11952 · Pratt & Whitney JT8D Series Turbofan Engines
Pratt & Whitney JT8D Series Turbofan Engines
Pratt & Whitney (PW) Models JT8D-1, -1A, -1B, -7, -7A, -7B, -9, -9A, -11, -15, -15A turbofan engines, installed on but not limited to Boeing 727 and 737 series, and McDonnell Douglas DC-9 series airplanes.
Note 1: This airworthiness directive (AD) applies to each engine identified in the preceding applicability provision, regardless of whether it has been modified, altered, or repaired in the area subject to the requirements of this AD. For engines that have been modified, altered, or repaired so that the performance of the requirements of this AD is affected, the owner/operator must request approval for an alternative method of compliance in accordance with paragraph (f) of this AD. The request should include an assessment of the effect of the modification, alteration, or repair on the unsafe condition addressed by this AD; and, if the unsafe condition has not been eliminated, the request should include specific proposed actions to address it.
This amendment adopts a new airworthiness directive (AD), applicable to Pratt & Whitney (PW) JT8D series turbofan engines, that requires inspections of main fuel pump control shafts for excessive spline wear. Additionally, as terminating action to the inspections, this action requires the replacement of the main fuel pump control shaft with parts of improved design, and reworking the main fuel pump impeller, impeller gear train plate assembly, and impeller cover assembly. This amendment is prompted by reports of failed main fuel pump control shafts caused by excessive spline wear. The actions specified by this AD are intended to prevent loss of engine throttle control, uncommanded acceleration, uncommanded deceleration or inflight shutdown, which could result in reduced airplane control during a critical phase of flight.
To prevent loss of engine throttle control, uncommanded acceleration, uncommanded deceleration or inflight shutdown, which could result in reduced airplane control during a critical phase of flight, accomplish the following:
(a) Inspect and, if necessary, replace the main fuel pump control shaft in accordance with procedures and intervals described in paragraphs 1.B. and 1.C. of the Accomplishment Instructions of PW Alert Service Bulletin (ASB) A6381, dated March 15, 2000, as follows:
(1) For fuel pumps that have incorporated the modifications of paragraph (c)(1) but not the modifications of paragraph (c)(2) as of the effective date of this AD, perform the initial inspection at the next main fuel pump accessibility after accumulating 6000 hours time in service (TIS) since last main fuel pump overhaul.
(2) For fuel pumps that have not incorporated the modifications of paragraph (c)(1) as of the effective date of this AD, perform the initial inspection at the next main fuel pump accessibility after accumulating 3000 hours TIS since last main fuel pump overhaul.
(b) Thereafter, reinspect the main fuel pump control shaft and remove and replace, if necessary, in accordance with intervals and procedures described in paragraphs 1.B. and 1.C. of the Accomplishment Instructions of PW ASB A6381, dated March 15, 2000.
(c) At the next main fuel pump overhaul perform the following:
(1) Install a reworked impeller, impeller gear train plate assembly and impeller cover assembly in accordance with paragraph 2.A of PW ASB A6381, dated March 15, 2000.
(2) Replace the main fuel pump control shaft with a serviceable main fuel pump control shaft.
(3) The next main fuel pump overhaul must occur no later than:
(i) 12,000 hours time in service (TIS) since last fuel pump overhaul; or
(ii) 2000 hours TIS from the effective date of this AD; or
(iii) 3000 hours TIS from the effective date of this AD, provided the main fuel pump has incorporated the modifications of paragraph (c)(1) as of the effective date of this AD and the inspection results from paragraph (a) of this AD are less than or equal to 15 degrees; whichever occurs latest.
(4) Modifications required by paragraph (c)(1) and (c)(2) of this AD constitute terminating action to the inspections required by paragraphs (a) and (b) of this AD.
(d) It is not necessary to perform the inspections required by paragraphs (a) and (b) or to adhere to the schedule of paragraph (c)(3) of this AD if the main fuel control modifications of paragraph (c)(1) and (c)(2) are performed throughout an operator's fleet in accordance with the schedule of Table 1 or Table 2 of this AD as follows:
(1) For fuel pumps that have incorporated the modifications of paragraph (c)(1) but not the modifications of paragraph (c)(2) as of the effective date of this AD, perform modifications in accordance with the schedule of Table 1.
(2) For fuel pumps that have not incorporated the modifications of paragraphs (c)(1) as of the effective date of this AD, perform the modification in accordance with the schedule of Table 2.
| Time in service since last main fuel pump overhaul: | Perform modifications of paragraph (c)(2) of this AD: |
|---|---|
| Greater than or equal to 15,000 hours TIS on the effective date of this AD | Within 1,000 hours TIS from the effective date of this AD. |
| Greater than or equal to 12,000 hours and less than 15,000 hours TIS on the effective date of this AD | Within 2,000 hours TIS from the effective date of this AD. |
| Greater than or equal to 8,000 hours and less then 12,000 hours TIS on the effective date of this AD. | Within 3,000 hours TIS from the effective date of this AD. |
| Less than 8,000 hours TIS on the effective date of this AD | Within 4,000 hours TIS from the effective date of this AD or 8,000 TIS since last main fuel pump overhaul, whichever occurs later. |
| Time in service since last main fuel pump overhaul: | Perform modifications of paragraph (c)(1) and (c)(2) of this AD: |
|---|---|
| Greater than or equal to 12,000 hours TIS on the effective date of this AD | Within 1,000 hours TIS from the effective date of this AD. |
| Greater than or equal to 10,000 hours and less than 12,000 hours TIS on the effective date of this AD | Within 2,000 hours TIS from the effective date of this AD. |
| Greater than or equal to 6,000 hours and less than 10,000 hours TIS on the effective date of this AD | Within 3,000 hours TIS from the effective date of this AD. |
| Less than 6,000 hours TIS on the effective date of this AD | Within 4,000 hours TIS from the effective date of this AD or 6,000 hours TIS since last main fuel pump overhaul, whichever occurs later. |
(e) For the purpose of this AD:
(1) Accessibility of the main fuel pump is defined as removal of the fuel control from the fuel pump on the engine or removal of the fuel pump from the engine.
(2) Main fuel pump overhaul is defined as compliance with the manufacturer's recommended overhaul procedures described in Argo-Tech Overhaul Manual 73-11-1.
(3) A serviceable main fuel pump control shaft is defined as Argo Tech part number 219093 or Rogers Dierks part number RD219093.
The aircraft, engines and makers this AD names, by the model designations in its text. A model listed here may still be outside the AD's serial ranges.
