Operators of MD-11 have been inundated lately with more than a dozen airworthiness directives.

Operators of MD-11 have been inundated lately with more than a dozen airworthiness directives. The activity considers what some observers have described as a "patchwork quilt" reply to what seems to be an increasing list of deficiencies with the MD-11

In brace installments, the Federal Aviation Administration (FAA) issued 15 airworthiness directives (AD's) forward the MD-11. Most were original AD's; a pair superseded previously issued AD's. In the 18 month since the crash of the Swissair Flight 111 the number of AD-related actions upon the MD-11 totals 46. As a basis for comparison, in the 18 month before the generation 2, 1998 crash the FAA issued 11 AD's upon the MD-11. Critics may papal court in these relative counts obmutescent evidence of a "tombstone" approach to safety - that it takes a crash to galvanize action.

The latest AD's are consistent with previously published directives forward the MD-11, which focused primarily in succession a number of electrically-related "nasty threats" (see ASW, Feb 8 1999) each one of the latest AD's relate in united way or another to the MD-11's electrical regularity These AD's came out in couple batches, eight on Feb. 1 and another seven onward Feb. 17. Operators have until March 17 to commentary on the first set, and until March 23 to elucidation on the second set.

The operative spells in these AD's are "inspect," "repair" and "modify."

In a cases, power feeder cables are to be injury in spiral wrap to obstruct chafing. One benefit of spiral wrapping is that it watchs to dampen inflight high common occurrence vibration-induced chafing. The evident intent is to impede the fiery result of electrical arcing.

In other instances, the installation of protective sleeving and spiral wrap may throw back a grudging admission that unsheathed Kapton wire bewilders a hazard (although the AD's certainly make no so admission and, indeed, some master-hands believe properly-installed Kapton wiring is safe).

The requirement to install recent circuit breakers and wiring "to hinder a disparity between the ratings of certain circuit breakers and their associated wiring" intimates an original-equipment electrical design fault (incompatible CB's and connector ratings). If in this way the original flaw is neatly camouflaged from the corrective action now mandated.

The requirement to perform electrical resistance measurements of loam studs and circuit breakers associated with the No. 2 generator infer improper build-up of grounding posts The action now required could be an offshoot of the production line moot points noted at the Long Beach, California plant in the early 1990's, when many of the MD-11's now in service were built (see ASW, Feb 28)

In light of the AD's, operators may be left wondering what become malignants unseen elsewhere in the MD-11?

Note: Listed below are ADs dated February 1 and February 17 which are in addition to the February 1 ADs concerning the MD-11 published brace weeks ago (see ASW, Feb 21) The contact for all of the ADs is britzska Portwood, 562/627-5350; fax 562/627-5210.

February 1

McDonnell Douglas archetype MD-11 and MD-11F: NPRM, propos AD obviates existing AD to add a modern requirement to accomplish a detailed visual inspection of the external power feeder cables to discover chafed or damaged wires; and repair, if necessary. The actions are intended to obstruct arcing from occurring under the forward cargo compartment floor as a come of damaged external power feeder cables. remarks due March 17. Docket No. 99-NM-265-AD.

McDonnell Douglas design MD-11: NPRM, proposed AD to require a general visual inspection to verify that the circuit breaker panel to the full opens, followon inspections, and corrective actions, if necessary. The actions are intended to render certain that the upper main circuit breaker panel explains fully. Comments due March 17 Docket No. 99-NM-266-AD.

February 17

McDonnell Douglas pattern MD-11: AD, final rule, obviates existing AD for certain airplanes to require the installation or modification of a flapper door ramp deflector onward the forward entry drop ceiling pile For certain other airplanes, this amendment requires inspection of the wire assembly support installation for evidence of chafing, and corrective actions, if necessary. The actions are intended to preclude such chafing. Effective March 23 Docket No. 99-NM-168-AD; Amendment 39-11569; AD 2000-03-10

McDonnell Douglas gauge MD-11 Series: AD, final empire requires a one-time visual inspection of the 90 percent brake pedal position switch to determine if certain date collection of lawss are present; and corrective action, if necessary. The actions are intended to impede the threaded insert connector from pulling liberated from the casing of the 90 percent brake pedal position switch and burning within the nose wheel steering cable. Effective March 23 Docket No. 99-NM-174-AD; Amendment 39-11575; AD 2000-03-16

McDonnell Douglas mould MD-11 Series: AD, final sway requires modification of the battery field cable installation in the center accessory compartment. The actions are intended to impede such arcing. Effective March 23 Docket No. 99-NM-172-AD; Amendment 39-11573; AD 2000-03-14