# [Notice of Proposed Rule Making (NPRM) Comment Form]{.underline}

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  **[NPRM Number:]{.underline}**      **[Date:]{.underline}** April 7,
  2007-NM-166-AD                      2008

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**Comment 1:**

# [Position]{.underline}: Propose revised text

**[Proposed Text/Comment]{.underline}:**

**Summary** paragraph, last sentence; **Sec. 39.13 \[Amended\]**, **Item
2**, **Unsafe Condition (d)**, last sentence:

Existing Text (in both places):

These certain icing conditions could cause a multiple engine flameout
during flight without the ability of the engines to be relit, and
consequent forced landing of the airplane.

Proposed Text (in both places):

These certain icing conditions may cause a multiple engine flameout
during flight, with the potential inability to restart the engines and
consequent forced landing of the airplane.

**[Reason for Proposed Text/Comments:]{.underline}**

Existing wording overly conveys the likelihood of not being able to
restart the engine(s) after flameout. While that possibility exists, to
date, all engines involved in all of the flameout events have been
restarted in flight with subsequent normal landing.

**Comment 2:**

# [Position]{.underline}: Propose revised text

**[Proposed Text/Comment]{.underline}:**

**Discussion** paragraph, first sentence:

Existing Text:

We have received reports indicating that there have been six (two dual)
engine flameout events on McDonnell Douglas Model MD-11 airplanes, in
ice-crystal icing conditions during descent.

Proposed Text:

We have received reports indicating that there have been seven engine
flameout events (two dual) on McDonnell Douglas Model MD-11 airplanes,
in ice-crystal icing conditions during descent.

**[Reason for Proposed Text/Comments:]{.underline}**

Boeing has reports of seven engine flameout events (two dual) on the
MD-11 airplane due to ice-crystal icing conditions.

**Comment 3:**

# [Position]{.underline}: Propose revised text

**[Proposed Text/Comment]{.underline}:**

**Discussion** paragraph, last sentence:

Existing Text:

This condition, if not corrected, could result in a multiple engine
flameout during flight without the ability of the engines to be relit,
and consequent forced landing of the airplane.

Proposed Text:

This condition, if not corrected, may result in a multiple engine
flameout during flight, with the potential inability to restart the
engines and consequent forced landing of the airplane.

**[Reason for Proposed Text/Comments:]{.underline}**

Existing wording overly conveys the likelihood of not being able to
restart the engine(s) after flameout. While that possibility exists, to
date, all engines involved in all of the flameout events have been
restarted in flight with subsequent normal landing.

**Comment 4:**

# [Position]{.underline}: Propose revised text

**[Propose Text/Comment]{.underline}:**

Existing text in part -- **Airworthiness Directive, section 39.13,
paragraph 2(f):**

"Prior to reducing thrust for descent in visible moisture when TAT is 6
\[deg\]C and below, the ENG IGN OVRD switch and the ENG, WING, and TAIL
ANTI-ICE switches must be placed in the ON position."

Proposed text:

"Prior to reducing thrust for descent, when icing conditions (defined by
visible moisture in the air and TAT is 6 Deg C or below) are present,
the ENG IGN OVRD switch and the ENG, WING, and TAIL ANTI-ICE switches
must be placed in the ON position. When icing conditions are no longer
present or anticipated, place the ENG IGN OVRD switch and the ENG, WING,
and TAIL ANTI-ICE switches in the OFF position."

**[Reason for Proposed Text/Comments]{.underline}:**

Provide additional procedural information as noted in the current
Interim Operating Procedures for icing conditions that exist or are
anticipated prior to descent.